Analytical techniques for cell fractions. XXII. Two-dimensional analysis of serum and tissue proteins: multiple gradient-slab gel electrophoresis

Human skeletal muscle myosin light chains analyzed by immobilized pH gradients during ontogenesis: identification of new phosphorylatable isoforms of light chain 2

Previous studies using two-dimensional gel electrophoresis have described adult and fetal isoforms of skeletal muscle myosin light chains (MLC). They have also revealed an embryo-specific light chain (LC1emb), apparently absent in most adult skeletal muscles. In order to characterize more thoroughly the MLC family, we have analyzed the MLCs from human skeletal muscle at different developmental stages using a two-dimensional electrophoresis technique with an immobilized pH gradient in the first dimension. The high resolution of this novel technique, resolving components which in isoelectric points are less than or equal to 0.01 pH, combined with sensitive silver staining, has allowed us to identify four phosphorylatable isoforms of MLC2: two slow-myosin light chains (MLC2Sa and b), two fast myosin light chains (MLC2Fa and b), and their phosphorylated counterparts: MLC2SaP and bP, MLC2FaP and bP. The following major modifications during development were observed: (i) The embryonic LC (LC1emb) persists up to at least 26 weeks of fetal life. (ii) The polymorphism of LC2 is already evident at 10 weeks of development but only the nonphosphorylated forms of LC2S and LC2F seem to be present. The LC2Fa form is predominant. As early as 26 weeks of fetal life, the 4 phosphorylated forms are detected. In the adult, LC2Fb is a minor component. (iii) LC3F (fast) is already expressed at an early embryonic stage (10 weeks).

Specific expression of proteins and phosphoproteins in 3T3 T mesenchymal stem cells at distinct growth arrest and differentiation states

Murine mesenchymal stem cells can be induced to arrest their growth at a series of growth and differentiation states in the G1 phase of the cell cycle. These include the predifferentiation arrest state (GD) at which the integrated control of proliferation and differentiation is mediated, the growth factor/serum deficiency arrest state (GS), and the nutrient deficiency arrest state (GN). Cells at states of reversible nonterminal differentiation (GD') and irreversible terminal differentiation (TD) can also be isolated. In this paper we have employed 1- and 2-dimensional (D) gel electrophoresis to evaluate changes in specific proteins that occur during the various growth and differentiation states of 3T3 T mesenchymal stem cells. The protein composition of membrane, microsome and cytosol preparations of cells arrested at GD, GS and GN states was determined by 2-D gel electrophoresis. More than 50 distinct polypeptides could be identified for each arrest state in gels analysed by a silver staining procedure or by autoradiography following [35S]-methionine labelling. A second series of studies established that a more limited number of differences could be identified if phosphoproteins were analysed by 1-D gel electrophoresis in cells at the GS, GD, GD' and TD states. These results established that one distinct 37 kD phosphoprotein is present in all growth arrested cells and that two distinct differentiation-associated phosphoproteins with molecular weights of 29 kD and 72 kD are present in cells at the GD' and TD states. Thus, the composition of proteins and phosphoproteins in mesenchymal stem cells serves to characterize different states of growth arrest and differentiation.2+he identification of differential

The expression of myosin light chains and tropomyosin in human muscle biopsies with histochemical type 1 and type 2 fiber deficiency

Two-dimensional gel electrophoresis (2DE) was used to compare the protein composition of human muscle biopsies that were shown by histochemical staining to be deficient in either type 1 or type 2 fibers. Distinct quantitative differences were found in the myofibrillar protein composition of muscle from a 43-year-old woman with proximal limb weakness that showed almost total absence of type 1 fibers and muscle from a 2.5-year-old girl with congenital myopathy in which there was severe lack of type 2 fibers. These data indicate that human type 1 and type 2 muscle fibers express distinct isoforms of myosin light chains and alpha-tropomyosin.

Major histocompatibility complex (MHC) protein analysis by optimised two-dimensional electrophoretic methods

Human histocompatibility molecules HLA-Class I and Class II (DR, DQ, DP) were analysed using three two-dimensional protocols: nonequilibrium pH gradient electrophoresis (NEPHGE), isoelectric focusing-acidic gradient (IEF-AG) and isoelectric focusing-basic gradient (IEF-BG). The three methods differ in their carrier ampholyte combinations and electrophoretic conditions. They provide different pH gradients and therefore different electrofocusing profiles. The NEPHGE protocol was adequate for separating proteins across a broad range of pI mobilities, i.e. 4.4 pH units between the acidic and the basic end. In contrast, the IEF-AG and the IEF-BG protocols gave a separation power across a narrow pH range, 1.9 and 1.7 pH units respectively. Thus, whereas the NEPHGE protocol provides a tool for a global major histocompatibility complex (MHC) antigen profile analysis, the IEF-AG and -BG allows one to investigate subcomponents of the individual MHC chains. For example, NEPHGE analysis of the HLA Class I heavy chain revealed a single spot. However, IEF-BG revealed the presence of six equidistantly spaced spots spanning a short pH gradient with identical molecular weight. Similar improved resolution was seen for the HLA-DR, DQ, and DP molecules. The IEF acidic gradient was adequate for separating the alpha chain; the IEF basic gradient gave better resolution of the beta chains. This data provides a baseline set of conditions for both analytical and preparative MHC protein studies prior to amino acid sequencing.

Differential cytokeratin expression in normal, hyperplastic and malignant epithelial cells from human prostate

Studies were undertaken to define the expression of cytokeratins in normal, hyperplastic and malignant epithelial cells from human prostate. Cytokeratin (CK) polypeptides, separated by two-dimensional electrophoresis, were identified by immunoblotting with CK-specific monoclonal antibodies. CK polypeptides 5, 7, 8, 15, 18 and 19 were identified in fresh normal and hyperplastic prostate. Expression of CK 15 has not been previously reported in human prostate. Analysis of central and peripheral zone tissues from human prostate did not reveal qualitative differences in CK expression between these areas. Epithelial cells harvested from fresh BPH tissue by percoll gradient centrifugation and propagated in vitro using selective culture techniques showed alterations in CK expression compared to intact human prostate. Specifically, CKs 6, 14, 16 and 17 were noted in cultured BPH epithelial cells but not fresh normal prostate or BPH tissue. Immunoblot analysis of the established prostate cancer cell lines PC3, DU145 and LNCAP showed expression of CKs 8 and 18 but not CKs 5, 7 and 15 which were observed in benign prostate. These studies further characterize CK expression in benign and malignant human prostate and provide insights which may be useful in differentiating normal, hyperplastic and malignant epithelial cells in the human prostate gland.

Proteins of the rat prostate. III. Effect of testosterone on protein synthesis by the ventral prostate of castrated rats

Protein synthetic activities in the ventral prostate were assessed by two-dimensional electrophoresis in either four-day or seven-day castrated rats at different intervals following subcutaneous implantation of testosterone-filled silastic tubings for a period of up to four days. Prostatic tissues were cut into one to two mm. pieces and incubated in tissue culture medium containing S35-methionine (100 microCi/ml.) at 37C under 95% oxygen and 5% carbon dioxide for four hours. The incubated tissues were subjected to two-dimensional electrophoresis and radiofluorography. Analysis of protein spots detected in the fluorograms by computer-assisted densitometry revealed temporal changes in the synthesis of individual proteins by the ventral prostate of castrated rats following androgen treatment. Changes in two groups of proteins were evaluated: castration-induced proteins and androgen-dependent proteins. The level of synthesis of three castration-induced proteins (spots G, H, and I) declined rapidly upon testosterone treatment and reached a non-detectable level for spots G and H and a low level of synthesis for spot I by three days following androgen treatment. Synthesis of androgen-dependent proteins (spots D, E, and F) was activated by testosterone treatment. However, the time interval required to activate the synthesis of these proteins is different. Synthesis of protein spot D (prostatic binding protein) was detected as soon as half hour after the treatment. Synthesis of spots E and F, on the other hand, was not activated until 24 and 48 hours after the treatment, respectively. These changes in patterns of protein synthesis represent the characteristics of cellular responses to testosterone stimulation by the regressed prostate.

Chromatographic separations of serum proteins on immobilized metal ion stationary phases

The separation of proteins on stationary phases consisting of a bound organic chelator and a chelated divalent transition metal has been studied as a function of (A) metal ion species; (B) mobile phase composition and pH; and (C) anion and cation concentration. Optimum separation was observed at alkaline pH on chelated nickel stationary phases. Ammonium and Tris salts reduced the affinity of the metal chelate packing for serum proteins. Halide ions caused the proteins to be more strongly bound to the stationary phase. High salt concentrations had only a small effect on the binding of serum proteins in the absence of amine containing buffers or salts. It was also observed that the ease of elution and the recovery of protein were dependent on pH and upon the presence of halides. The general order of elution of serum proteins, based on isoelectric focusing, was independent of metal ion species and elution conditions, suggesting that a single mechanism or a unique sequence of mechanisms was operative. The results suggest that ligand exchange is the major mechanism of separation under basic conditions and that hydrophobic effects are the result of the competition of nonnitrogen ions with ammonium ions or amines for ligand binding sites modifying or participating in protein binding. Protein binding studies under weak acidic conditions are also presented although the mechanism responsible for protein binding is unclear.

Demonstration of the role of prostate-specific antigen in semen liquefaction by two-dimensional electrophoresis

Two-dimensional protein profiles of human semen, prostatic fluid, and seminal vesicle fluid were compared to demonstrate changes in the protein composition of human semen before and after liquefaction. Semen specimens were obtained from a volunteer. Prostatic fluid specimens were collected by rectal massage from patients visiting a urology clinic. Samples of seminal vesicle fluid were collected by needle aspiration from isolated seminal vesicles, which were removed at surgery. All specimens were prepared and processed according to the ISO-DALT system for separation of proteins in two-dimensional gels. Following electrophoresis, protein spots in the gels were visualized by silver staining. Prostatic fluid and seminal vesicle fluid showed their characteristic protein profiles. The protein profile of human semen contained specific proteins of both prostatic fluid and seminal vesicle fluid. One major group of proteins in seminal vesicle fluid (Mw 28,000-68,000 daltons), designated as seminal vesicle-specific antigen, was observed in freshly ejaculated human semen, but disappeared from the two-dimensional profile when the ejaculate was allowed to stand at room temperature for 30 min. When prostatic fluid or prostate-specific antigen was mixed with seminal vesicle fluid and incubated at 37C for 30 min, the seminal vesicle-specific antigen also disappeared from the two-dimensional profiles. The findings indicate that seminal vesicle-specific antigen, a group of predominant proteins in seminal vesicle fluid, is the structural component of seminal coagulum, and that prostate-specific antigen is the enzyme which digests seminal vesicle-specific antigen and liquifies semen coagulum.

Synthesis of functional bovine leukemia virus (BLV) p34tax protein by recombinant baculoviruses

The bovine leukemia virus (BLV) p34tax (also called tat, p34, XLOR gene product) is a 34-kDa polypeptide encoded in the 3'-terminal region of the virus. This protein is responsible for positive transcriptional trans-activation of promoter elements located within the BLV long-terminal repeat. We introduced the protein-coding region of BLV p34tax into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus. After infection of the insect Spodoptera frugiperda (SF9) cell line, this recombinant strain of baculovirus produced approximately 100 to 150 mg of p34tax per 2 X 10(9) cells. This protein, when introduced into mammalian fibroblasts by using a cell-to-cell fusion technique, functionally trans-activated the BLV long-terminal repeat. Analysis of 32P-labeled proteins of SF9 cells expressing BLV tax by two-dimensional gel electrophoresis indicated that the BLV p34tax was phosphorylated.

History of electrophoretic methods

Electrophoresis is the migration of electrically charged particles or ions in solutions due to an applied electric field. The ability to separate very similar substances including different proteins for analytical and preparative purposes has increased, especially since 1950, owing to the introduction of zone electrophoresis in paper and later in gels of polyacrylamide or agarose. After 1960, disc and displacement electrophoresis (isotachophoresis) and isoelectric focusing offered much increased resolution. Electrophoretic methods nowadays promote advances in biochemistry and molecular biology and will continue to be very important in science and for numerous applications in genetics, gene technology, sequencing of nucleic acids and proteins, studies of diseases and malfunctions including cancer, and in the identification of species and individuals, e.g., in forensic medicine.

Consecutive radiofluorography and silver staining of two-dimensional gel electrophoretograms: application in determining the biosynthesis of serum and tissue proteins

The methodology for conventional radiofluorography of two-dimensional gels, followed by rehydration of the gel and subsequent silver staining, is described. The image obtained by radiofluorography is referred to as biosynthetic image, and the image obtained by silver staining as constitutive image. Since the two images are already in close register (the same gel), reliable identification of polypeptides by the two different assays is possible, and the comparison provides valuable information on the catabolism of each entity. The utility of this procedure is illustrated in experiments involving a labeling with L-[35S]methionine of an entire mouse. Both serum and tissue samples were analyzed by two-dimensional gel electrophoresis with the aim of determining several categories of polypeptides in terms of their biosynthetic rates and their composition.

Isolation and sequence analysis of proteins from mouse forebrain using two-dimensional gel electrophoresis coupled to high-pressure liquid extrusion

This report presents a technique for recovery of mouse forebrain proteins from two-dimensional sodium dodecyl sulfate-polyacrylamide gels for subsequent primary structure determination. Proteins were visualized by Coomassie staining or salt precipitation and manually cut out of the gel. Excised spots were minced and loaded into an empty precolumn of a reversed-phase high-performance liquid chromatography system. Purified protein was extruded from a gel matrix by pressurized liquid, then separated from gel contaminants by reversed-phase gradient elution, and finally collected in siliconized tubes or on polybrene-coated filter disks for gas-phase sequencing. Several mouse and rat forebrain proteins were purified by this method and sequenced. Three previously unidentified mouse brain proteins with molecular weights of 4,000, 12,000, and 18,500 were partially sequenced and three hemoglobin fragments were structurally identified and mapped. Ribonuclease A, myoglobin, adrenocorticotropin, and bovine somatotropin were also subjected to two-dimensional (2-D) analysis and partially sequenced. Recovery values of 27-95% were obtained for extruded 14C-labeled ribonuclease, carbonic anhydrase, and bovine serum albumin out of sodium dodecyl sulfate-polyacrylamide gel electrophoretic gels. Losses resulting from the multiple handling steps of a 2-D gel separation process were also investigated. Recoveries of 12-17%, as determined by sequencing signals, were achieved. These latter recovery values reflect overall losses incurred in gel-focusing, gel-sizing, staining, destaining, high-pressure liquid extrusion, and N-terminal blockage. This work demonstrates that an array of protein spots can be systematically identified or defined by partial sequencing after high-pressure liquid extrusion from a 2-D gel matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Germ cell-Sertoli cell interactions. Studies of cyclic protein-2 in the seminiferous tubule

This review briefly describes the discovery and isolation of a novel Sertoli cell product, cyclic protein-2, (CP-2) and the generation of an antiserum against this protein. Using this antiserum, we demonstrated a stage-specific change in the synthesis of CP-2 by Sertoli cells within intact seminiferous tubules; synthesis is maximal at stages VI and VIIa,b of the cycle and minimal at stage XII. That CP-2 is a product of Sertoli cells was confirmed by immunohistochemical analysis. Comparison of CP-2 and transferrin synthesis by immature (17-day) and mature (75-day) Sertoli cells within intact seminiferous tubules has documented a significant increase in the synthesis of both proteins during testicular maturation. It was noteworthy, however, that the increase in CP-2 synthesis was much greater than the increase in transferrin synthesis. These data in conjunction with previous comparisons of the stage-specific changes in CP-2 and transferrin synthesis and secretion led to the hypothesis that the synthesis of these two proteins is regulated by different cellular interactions. Examination of cultured Sertoli cells obtained from mature rats demonstrated that transferrin synthesis and secretion were stimulated by hormones and vitamins, whereas CP-2 synthesis and secretion were not significantly affected by the same factors. Therefore, these data demonstrate that hormonal regulation of transferrin synthesis by Sertoli cells differs from hormonal regulation of CP-2 synthesis. Indeed, our data suggest that CP-2 synthesis is not directly regulated by hormones and vitamins. Finally, we demonstrated that when Sertoli cells are separated from germ cells and the Sertoli cells placed in culture, the age-dependent increase in CP-2 synthesis, noted with cultured tubules, is lost. In contrast, significantly more transferrin is synthesized by primary cultures of Sertoli cells obtained from old animals than from young animals. Taken together, all of these data indicate that the regulation of CP-2 synthesis and secretion by the Sertoli cell is unique and is primarily stimulated by paracrine signals or direct cell contact with the germ cells. Which of these mechanisms of cell-cell communication in the testis is important to regulation of CP-2 synthesis by Sertoli cells is unknown. Neither do we know which spermatogenic cell type provides this stimulus. These issues can now be addressed, however, because we have developed the protocols for isolating and culturing Sertoli cells from mature rat testes.

Two-dimensional protein profiles of cultured stromal and epithelial cells from hyperplastic human prostate

Studies were undertaken to compare and contrast the two-dimensional protein profiles of epithelial and stromal cells from hyperplastic human prostate to establish the protein composition of the two major cellular components of the prostate. Epithelial and stromal cells were isolated from human prostate obtained from patients undergoing open prostatectomy for benign prostatic hyperplasia (BPH). Proteins, isolated from the two cell populations and separated by two-dimensional (2D) electrophoresis, were analyzed by silver staining, fluorography of [35S]-methionine-labeled proteins, and immunoprotein blotting. Isolated prostatic epithelial cells, but not stromal cells, contained cytokeratin polypeptides 5, 6, 7, 8, 13, 14, 15, 16, 17, 18, and 19. Although vimentin could not be identified in silver stained 2D gels and fluorographs of cultured prostatic epithelial cells, a low level of immunoreactivity was noted following immunoblot analysis of epithelial cells proteins by the use of an anti-vimentin polyclonal. Vimentin was prominently expressed in cultured prostatic stromal cells and could be identified on silver stained 2D gels, fluorographs, and immunoblots of stroma-derived proteins. In addition, stromal marker proteins SM1, SM2, and SM3 were identified in 2D gels of stromal cells to distinguish them from epithelial cells. These studies demonstrate (1) the two-dimensional protein profile and cytokeratin polypeptide composition of cultured epithelial cells from hyperplastic human prostate and (2) the 2D protein profile of cultured prostatic stromal cells and identification of specific stromal marker proteins.

Detection of hybrid phenotypes in African trypanosomes by high resolution two-dimensional gel electrophoresis

High resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and autoradiography were used to analyze the protein phenotypes of Trypanosoma brucei (T.b. brucei and T.b. gambiense) clones suspected of being hybrids. Procyclic culture forms of parental and suspected hybrid trypanosomes were biosynthetically labeled with [35S]methionine and labeled proteins were resolved by multiple 2D-PAGE (the ISO-DALT system) to allow accurate inter-gel comparisons. Autoradiography of the gels showed that the parental clones had qualitative differences in at least seven sets of spots. Five of these sets represented charge differences and one represented proteins of altered relative molecular mass (Mr) and charge. Autoradiographs of the gels of the putative hybrid trypanosomes showed both forms of the proteins found separately in the parental clones indicating that new, nonparental phenotypes had been generated by transmission of mixed trypanosome clones through tsetse flies. The 2D-PAGE patterns from parasites cultivated for extended periods were identical, showing that the individual cloned parasites were phenotypically stable. The results indicate that analytical 2-D gels can be used to study the phenotypes of "parental" or "hybrid" African trypanosomes without having any previous knowledge of the molecular characteristics of the parasites. In addition, the technique allows an extension of phenotypic analysis to hundreds of different proteins in populations of cloned parasites.

Phenotypic characterization of Theileria parva schizonts by two-dimensional gel electrophoresis

Biosynthetically radiolabelled Theileria parva schizonts were purified from bovine lymphoblastoid cells and their proteins were analyzed by two-dimensional gel electrophoresis and autoradiography. The protein spot patterns of schizont proteins from three stocks of T. parva parva indicated that the phenotypic diversity among the stocks was minimal, with the Mariakani and Uganda stocks being identical and the Muguga stock showing only a few differences in minor spots. Comparison of the spot patterns of schizonts of three T. parva subspecies showed that T.p. parva and T.p. bovis differed in only one protein and thus could not be reliably distinguished on the basis of their protein differences. However, T.p. lawrencei showed several protein differences and could be distinguished easily from the other subspecies. Differences in schizont-protein spot patterns were also seen when two different cell lines were infected with the same Theileria stabilate, when one cell line was infected with two different stabilates of the same stock and when uncloned and cloned infected cell lines were used. These results suggest the possibility that selection of phenotypically different parasites could occur in vivo or in vitro.

Heritable protein variants induced by exposure to ethylnitrosourea: heritability, subcellular location, and tissue distribution

The heritability, subcellular location, and tissue distribution of liver protein alterations found in the two-dimensional electrophoresis patterns of 4 offspring from male mice treated with N-ethyl-N-nitrosourea (ENU) were studied. Mice homozygous for each of the 4 ENU-induced protein variants were found to be viable and fertile, although the number of homozygous offspring from crosses between heterozygous carriers of one variant (ENU 2) was less than that expected for a nondetrimental trait. Two of the proteins altered by ENU-induced mutations were associated with the crude mitochondrial fraction, another was found predominantly in the microsomal fraction, and the fourth was associated with the mitochondrial, microsomal, and cytosol fractions. All of the ENU-induced mutations affected proteins that were not liver-specific; i.e., the proteins were found in other tissues in addition to the liver.

Extraction of plant proteins for two-dimensional electrophoresis

Three different extraction procedures for two-dimensional electrophoresis of plant proteins are compared: (i) extraction of soluble proteins with a nondenaturing Tris-buffer, (ii) denaturing extraction in presence of sodium dodecyl sulfate at elevated temperature allowing the solubilization of membrane proteins in addition to a recovery of soluble proteins, and (iii) a trichloroacetic acid-acetone procedure allowing the direct precipitation of total proteins.

Genetic polymorphism of a lymphocyte protein (p75) with six different alleles studied by two-dimensional electrophoresis: qualitative and quantitative data

The genetic polymorphism of a human lymphocyte protein (p75) was studied by two-dimensional electrophoresis within 17 families and, in addition, 22 unrelated individuals from Southern Germany, resulting in a total of approximately 100 individuals. The cytosolic and membrane proteins from cell lysates of phytohemagglutinin stimulated and [3H]leucine labeled lymphocytes were separated by two-dimensional electrophoresis. The p75 protein with an approximate molecular weight of 75,000 occurred in six variants with slightly different isoelectric points and/or apparent molecular weights. Three common variants (a, b, and c) and three rare variants (d, e and f) could be distinguished. Among the approximately 100 individuals studied we observed 15 different phenotypes, three homozygous (p75-a, -b, -c) and 12 heterozygous (p75-ab, -ac, -bc, -ad, -ae, -be, -bf, -cd, -ce, -cf, -de, -df) phenotypes. The genetics of the p75 protein variations was ascertained by family studies and quantitative computer analysis. We were able to show a Mendelian mode of inheritance of the variants within the families and a gene-dosage dependence of the protein spots in homozygous and heterozygous phenotypes. The data allowed us to assume a polymorphic protein p75 determined by six alleles on a autosomal gene locus. The allele frequencies were calculated from the phenotype distribution within 56 unrelated individuals. The gene frequencies of the three common alleles ranged between 0.38 and 0.22 and the gene frequencies of the three rare alleles ranged between 0.01 and 0.07.

The separation of whale myoglobins with two-dimensional electrophoresis

Five myoglobins (sperm whale, Sei whale, Hubbs' beaked whale, pilot whale, and Amazon River dolphin) were examined using two-dimensional electrophoresis. Previous reports indicated that none of these proteins could be separated by using denaturing (in the presence of 8-9 M urea) isoelectric focusing. This result is confirmed in the present study. However, all the proteins could be separated by using denaturing nonequilibrium pH-gradient electrophoresis in the first dimension. Additionally, all the myoglobins have characteristic mobilities in the second dimension (sodium dodecyl sulfate), but these mobilities do not correspond to the molecular weights of the proteins. We conclude that two-dimensional electrophoresis can be more sensitive to differences in primary protein structure than previous studies indicate and that the assessment seems to be incorrect that this technique can separate only proteins that have a unit charge difference.

Analysis of human lymphocyte protein expression. I. Identification of subpopulation markers by two-dimensional polyacrylamide gel electrophoresis

This study provides new knowledge on the changes in protein expression that differentiate the functionally and phenotypically different cells of the human immune system. Purification by flow cytometry of normal lymphocytes (both T and B cells), monocytes and granulocytes, combined with high-resolution two-dimensional polyacrylamide gel electrophoresis, revealed reproducible qualitative and quantitative changes between these cell populations. Characteristic profiles of marker proteins for each cell type were identified. Determination of markers for T lymphocyte subpopulations was achieved by the comparative analysis of normal T cells separated on the basis of CD4 and CD8 expression in combination with the analysis of cells from patients with T cell chronic lymphocyte leukemia. These results suggest that the modulation or regulation of proteins is very strictly controlled in lymphoid differentiation, and that several quantitative and a few qualitative differences can give rise to completely different phenotypes. Thus, instead of detecting numerous random differences among lymphocyte protein patterns, rather stringent regulation of protein expression in each subpopulation was found.

Two-dimensional gel electrophoresis of platelet polypeptides with immobilized pH gradients in capillary tubes

Two-dimensional electrophoresis (2-DE) with immobilized pH gradient (IPG) gels in capillary tubes was used in the first-dimensional isoelectric focusing (IEF) for the separation of human platelet polypeptides. Two types of IPG tube gels, pH ranges 4-8 and 7-10, containing 8 M urea, 1% Nonidet P-40 and 0.1% pH 3.5-10 Ampholine carrier ampholytes (CA) were prepared by a simple method not requiring special equipment. The addition of CA to both gel and sample solutions was essential in the tube gel IPG system. Proteins were visualized by a modification of Wray's silver-staining technique. The degree of resolution and the number of spots observed on an IPG 2-DE gel with pH 4-8 were comparable with those obtained with O'Farrell's high-resolution 2-DE. Approximately 200 basic polypeptides, which are difficult to separate by conventional CA-based IEF 2-DE or the non-equilibrium pH gradient system, were well resolved by 2-DE with a pH 7-10 IPG tube gel in the first-dimension. The gel patterns with either pH gradient 4-8 or 7-10 were highly reproducible among gels prepared and run simultaneously. These results demonstrated the potential and usefulness of the 2-DE system with IPG gels in capillary tubes.

Two-dimensional electrophoresis of human lymphocyte proteins: two-dimensional polymorphisms and paternity testing

Genetic polymorphisms of seven human lymphocyte proteins, analyzed by two-dimensional electrophoresis, were evaluated in respect to their suitability for paternity testing. Current data of an enlarged family and population study for five proteins (p23, p30, p40, p60, p66), already described for a smaller population sample of Southern Germany, are presented together with evidence for a new polymorphic protein (p42), recently observed in our survey. These six proteins occurred in isoelectric focusing as two different variants, acidic (a) and basic (b). The genetic basis of the protein variations was ascertained (i) by the presence of homozygous and heterozygous phenotypes, (ii) by the Mendelian mode of transmission of the variants as allelic gene products within 17 families and (iii) by the demonstration of a gene-dosage dependence comparing the spot intensities in homozygous and heterozygous phenotypes. For quantitative data, laser densitometric scanning of the protein spots followed by computer-assisted quantitative evaluation of the spot intensities was performed. The allele frequencies of the polymorphic protein were calculated from the phenotype distributions within a sample of 56 unrelated individuals from Southern Germany. Gene frequencies of the common alleles ranged between 0.991 and 0.518. To discuss the suitability of the two-dimensional polymorphisms for paternity testing the theoretical exclusion probabilities were assessed for seven polymorphic proteins observed in our population sample, the six polymorphisms with two alleles described here and a further polymorphism (p75) with six alleles. For five proteins (p23, p40, p42, p66 and p75) we found sufficiently high values for the theoretical exclusion probabilities, ranging from 10% to 34%.(ABSTRACT TRUNCATED AT 250 WORDS)

Forensic aspects of haptoglobin: electrophoretic patterns of haptoglobin allotype products and an evaluation of typing procedure

A procedure used for haptoglobin (Hp) typing in paternity cases has been evaluated. All serum samples have been subtyped with a one-dimensional isoelectric focusing/immunoblotting method, and samples with rare or questionable patterns have been further examined by two-dimensional electrophoresis with isoelectric focusing in the first dimension followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. The electrophoretic Hp-patterns of common and rare alpha- and beta-chain variants are shown, including allotype patterns of two new beta-chain variants and three new alpha-chain variants. Retyping of nearly 2000 individuals at intervals between 1 to 12 months revealed a typing error frequency of about 0.3%, which is considered acceptable, provided new blood samples are required in every case of paternity exclusion. Comparison of typing results obtained with the present procedure and with routine starch gel electrophoresis in more than 5000 serum samples gave conflicting results in 6 samples. The sensitivity of the described one-dimensional subtyping method was slightly better than that of starch gel electrophoresis. In 4110 unrelated individuals, involved in cases of disputed paternity the Hp 2SS 0.038, Hp 2FF 0.004, and Hp 3 (Johnson) 0.0005. These allele frequencies give a theoretical paternity exclusion rate of 32.5%, which is in accordance with the observed rate in 2200 paternity cases with more than 600 non-fathers. It is concluded that the present procedure represents a definite improvement for Hp subtyping in practical paternity diagnostics. Preliminary results with retyping of weak Hp patterns using a staining technique involving the biotin/avidin complex indicate that the sensitivity of the one-dimensional subtyping method may be substantially increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid imaging, using a cooled charge-coupled-device, of fluorescent two-dimensional polyacrylamide gels produced by labelling proteins in the first-dimensional isoelectric focusing gel with the fluorophore 2-methoxy-2,4-diphenyl-3(2H)furanone

A new method for visualising proteins in two-dimensional polyacrylamide gels was developed. Proteins were labelled with the fluorophore 2-methoxy-2,4-diphenyl-3(2H)furanone (MDPF) while present in the first-dimensional gel after isoelectric focusing and subsequently electrophoresed into the second-dimensional gel. High resolution spot patterns were produced and compared with other methods of visualisation. A new rapid imaging system based on a cooled charge-coupled-device was used to view the two-dimensional fluorescent protein spot patterns. The method allows the immediate and rapid imaging of two-dimensional gels at the end of electrophoresis with no further processing.

Peptide mapping of polypeptides separated by two-dimensional electrophoresis: protease digestion directly on the two-dimensional gel followed by electrophoresis in reverse direction

A method is described which allows to reveal simultaneously the proteolytic patterns of numerous polypeptides separated by two-dimensional electrophoresis. After two-dimensional electrophoresis, the gels were dipped successively in buffers for preequilibration, protease digestion, and reequilibration. They were then returned to the electrophoresis tank, and electrophoresis was continued for a short time. After silver staining, digestion products appeared, lined up behind the original polypeptide spots. The method allows proteolytic patterns of numerous polypeptides to be visualized simply and quickly. Among proteins of wheat leaves, 31 groups of related polypeptides were found according to the similarity of their proteolytic patterns.

Comparison of rat and mouse ornithine aminotransferase with respect to molecular properties and regulation of synthesis

A comparative study of the synthesis patterns and molecular properties of mouse and rat ornithine aminotransferase (OAT) was conducted. The two enzymes were found to be very similar with respect to catalytic properties, two-dimensional electrophoresis patterns of tryptic digests, amino acid compositions, and antibody cross-reactivity. In vitro translation assays for OAT synthesis on free polysomes isolated from livers at different times of day showed similar circadian fluctuations in OAT synthesis for both species. However, hybridization measurements revealed no circadian changes in the levels of hybridizable OAT mRNA in these livers. These results demonstrate that the circadian cycling of OAT synthesis is regulated at the level of translation in both the rat and the mouse.

Molecular evolution among some Drosophila species groups as indicated by two-dimensional electrophoresis

The evolutionary and phylogenetic relationships of seven Drosophila species groups (represented by D. melanogaster, D. mulleri, D. mercatorum, D. robusta, D. virilis, D. immigrans, D. funebris, and D. melanica) were investigated by the use of two-dimensional electrophoresis. The resulting phylogeny is congruent with the current views of evolution among these groups based on morphological characters and immunological distances. Previous studies indicated that the ability of one-dimensional electrophoresis to resolve relationships between distantly related taxa extended to about the Miocene [25 million years (Myr) ago], but the present study demonstrates that two-dimensional electrophoresis is a useful indicator of phylogeny even back to the Paleocene (65 Myr ago). In addition, two-dimensional electrophoresis is shown to be a useful technique for detecting slowly evolving structural proteins such as actins and tropomyosins.

Identification, characterization, and functional correlation of calmodulin-dependent protein phosphatase in sperm

Preliminary data demonstrated that the inhibition of reactivated sperm motility by calcium was correlated with inhibited protein phosphorylation. The inhibition of phosphorylation by Ca2+ was found to be catalyzed by the calmodulin-dependent protein phosphatase (calcineurin). Sperm from dog, pig, and sea urchin contain both the Ca2+-binding B subunit of the enzyme (Mr 15,000) and the calmodulin-binding A subunit with an Mr of 63,000. The sperm A subunit is slightly higher in Mr than reported for other tissues. Inhibition of endogenous calmodulin-dependent protein phosphatase activity with a monospecific antibody revealed the presence of 14 phosphoprotein substrates in sperm for this enzyme. The enzyme was localized to both the flagellum and the postacrosomal region of the sperm head. The flagellar phosphatase activity was quantitatively extracted with 0.6 M KCl from isolated flagella from dog, pig, and sea urchin sperm. All salt-extractable phosphatase activity was inhibited with antibodies against the authentic enzyme. Preincubation of sperm models with the purified phosphatase stimulated curvolinear velocity and lateral head amplitude (important components of hyperactivated swimming patterns) and inhibited beat cross frequency suggesting a role for this enzyme in axonemal function. Our results suggest that calmodulin-dependent protein phosphatase plays a major role in the calcium-dependent regulation of flagellar motility.

Marker polypeptide differences between spontaneous strongly and weakly metastatic cancer cells identified by 2-dimensional gel electrophoresis

A recent 2-dimensional gel electrophoresis study revealed several polypeptide differences between a strongly metastatic and a weakly metastatic clone from a single chemically induced murine fibrosarcoma (Jellum et al., 1984). To exclude the possibility that this was merely coincidental, the study is extended here to 2 other fibrosarcomas recently and similarly induced in mice of the same inbred strain. Metastatic potential was defined by the number of lung metastases spontaneously formed from a transplanted primary footpad tumor. One strongly (or moderately) metastatic cell line and I weakly metastatic line from each of the 3 fibrosarcomas were examined in the same experiments. In confirmation of our previous results, the same polypeptides consistently occurred in considerably greater amounts in the weakly metastatic than in the strongly metastatic cells. One of these marker polypeptides was absent from the strongly metastatic cell lines. In comparison with 2 of the 3 most metastatic lines, the third line was only moderately metastatic, and differed least strongly from the 3 weakly metastatic cell lines with regard to expression of th marker polypeptides. Marker polypeptide expression showed no consistent correlation with tumorigenicity. No other consistent polypeptide differences between strongly metastatic and weakly metastatic cells could be identified among the approximately 2,000 cellular polypeptides separated on the gels.

Use of "submarine" gel electrophoresis for running multiple two-dimensional protein gels

An apparatus commonly used for the electrophoresis of submerged agarose gels was used to separate proteins in the second dimension, after isoelectric focusing in the first dimension. Multiple second-dimension gels were stacked one above the other and run horizontally, submerged in the sodium dodecyl sulfate-containing Laemmli buffer system. The reproducibility of the gels run under these conditions is remarkable and eliminates the need for individual vertical electrophoresis units for routine analysis. The units for submerged horizontal gel electrophoresis are easily made or are inexpensively available commercially.

Mode of fibroblast growth enhancement by human interleukin-1

Previous studies have demonstrated that interleukin-1 (IL-1) stimulates fibroblast growth (Schmidt, J. A., S. B. Mizel, D. Cohn, and I. Green. 1982. J. Immunol. 128:2177-2182) and binds to specific, high affinity receptors of BALB/c3T3 cells (Bird, T. A., and J. Saklatval. 1986. Nature (Lond.). 324:263-265, 266-268). We have investigated the mechanism of fibroblast growth stimulation by IL-1. Addition of fibroblast growth factor derived from platelets (PDGF) to a quiescent culture of BALB/c3T3 cells produced 8-10-fold increase in DNA synthesis during 24-h incubation. The cellular action of PDGF was mediated through competence induction and required synergistic action of plasma-derived factors for full mitogenic activity. When tested at a wide range of concentrations (0.1-100 pM), natural IL-1 or recombinant IL-1 produced only a maximum of 5-10% of DNA synthesis elicited in response to PDGF or serum. Induction of DNA synthesis required continuous presence of IL-1 and did not exhibit synergism with plasma. Competence induction and mitogenic stimulation by PDGF was associated with early induction of proteins P32, P38, P46-48, P75, and changes in cytoskeletal organization. Examination of these early cellular changes showed that IL-1 did not produce similar induction of cellular proteins and the morphological changes associated with growth stimulation. These results suggest that the mode of IL-1 action on BALB/c3T3 was not through competence induction. When IL-1 was added to cells rendered competent by brief exposure to PDGF, 10-15% additional DNA synthesis occurred during the first 24 h. Extended incubation of PDGF-treated cells in the presence of IL-1 revealed that the stimulation by IL-1 occurred predominantly during the subsequent cycle of DNA replication, wherein DNA synthesis reached three- to fivefold higher than the untreated cultures. We conclude (a) IL-1 alone is not a potent mitogen for BALB/c3T3 cells, and does not bring cells out of the growth arrest Go phase, (b) treatment with PDGF renders the cells more responsive to IL-1, (c) part of the IL-1 action on competent cells may be characterized as progression inducing activity, further, (d) our results indicate that action of IL-1 on PDGF-treated cells produces sustained DNA synthesis for an extended period, perhaps by preventing the entry of cells into growth arrest Go phase.

Comparison of posttranslational protein modification by amino acid addition after crush injury to sciatic and optic nerves of rats

Posttranslational protein modifications by the addition of amino acids are reactions which occur in intact sciatic and optic nerves of rats. The nerves differ, however, in that 2 h after crush injury these reactions are activated in sciatic but not in optic nerves. As sciatic nerves will eventually regenerate, whereas optic nerves will not, we have proposed that the activation of these reactions is correlated with the ability of a nerve to regenerate. The current experiments examined the posttranslational addition of amino acids to proteins at times greater than 2 h after nerve crush, during sciatic nerve regeneration and optic nerve degeneration. We also examined the optic nerve for morphologic correlates to changes in protein modification and partially characterized the proteins modified by [3H]Lys in the regenerating sciatic nerve using two-dimensional sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). In a segment of sciatic nerve taken from a region just proximal to the site of crush, protein modification by covalent addition of [3H]Arg, [3H]Lys and [3H]Leu increased during both posttraumatic (2 h postcrush) and regenerative (6 days and 14 days postcrush) stages. Two-dimensional PAGE of [3H]Lys modified sciatic nerve proteins 6 days after crush injury showed labeling of proteins having molecular masses in the 18,000- to 20,000-, 30,000- to 40,000-, and 80,000- to 100,000-Da ranges, with neutral or basic isoelectric points (pI 7.1 to 8.0). In the retinal portion of the crushed optic nerve, incorporation of the same amino acids was unchanged or depressed to 21 days postcrush, except at 6 days postcrush when the incorporation of all three amino acids into proteins was increased threefold. These increases correlated with the appearance of terminal end bulbs in the portion of nerve analyzed. Histological examination of each nerve 2 h postcrush showed marked edema in the optic but not the sciatic nerve, a condition which may be related to the ability of sciatic and inability of optic nerves to activate protein modification reactions.

Two-dimensional electrophoresis computerized processing

This paper describes various methods suitable for implementation of two-dimensional processing software. The different steps leading to a complete processing are described, from the digitalization of the image to the processing of the resulting data. The characteristics of a convenient digitalization system are discussed. The different software devoted to spot detection is reviewed with respect to the presence or otherwise of a spot model and its characteristics. The major techniques for gel matching are compared as are designs for database structures suitable for tabulation of measurements. Finally, the need for a sophisticated system of data processing is stressed and its main requirements are described.

A simple, inexpensive method for the salt-free concentration of proteins for analysis by two-dimensional gel electrophoresis

A rapid, inexpensive method for the salt-free concentration of small quantities of proteins for analysis by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) has been developed. Proteins adsorbed to diatomaceous earth are subsequently removed using either sodium dodecyl sulfate or urea solubilization reagents for 2D-PAGE analysis. This procedure has been found to concentrate proteins having wide ranges of molecular weight and charge. It is also valuable for the concentration of large numbers of small samples from cells cultured in vitro.

Mapping of synovial fibroblast proteins by high resolution two-dimensional polyacrylamide electrophoresis

The highly sensitive protein separation technique two-dimensional polyacrylamide gel electrophoresis was used to study the cellular protein synthesis in 1) cultured human rheumatoid and 2) normal synovial fibroblasts and 3) normal skin fibroblasts. No reproducible differences were found that could be ascribed to cellular origin, the disease or in vitro cellular aging. The reasons for that probably were related to the cell cultures and not to failure of protein detection.

Modifications and additions to the ISO-DALT system for two-dimensional gel electrophoresis

Modifications of ISO-DALT devices that further enhance the efficiency and reproducibility of two-dimensional mapping of proteins are described. The principal changes in ISO system devices include the introduction of a gel casting trough with a removable panel to permit the removal of excess gel without introducing air into the electrofocusing gels and the introduction of an upper electrode compartment with a separate watertight septum for each electrofocusing tube to permit tube removal for cleaning and replacement. The principal changes in DALT system devices include the use of modified powder funnels to introduce acrylamide solutions into the slab gel gradient former without aeration; the introduction of a flexible outlet system for the gradient former to facilitate the removal of air bubbles; the introduction of an inexpensive two-part mixing chamber to permit disassembly for cleaning; the use of split gel holders to eliminate deformation and breakage of electrofocusing gels during loading onto slab gels; the introduction of an inexpensive integrated slab gel casting/rotating apparatus; and the introduction of a simple, water-cooled slab gel electrophoresis apparatus to reduce the volume of running buffer used in electrophoresis.

Proteins of the rat prostate. II. Synthesis of new proteins in the ventral lobe during castration-induced regression

Ventral prostates from adult Sprague-Dawley rats at different days postcastration were cut into one to two mm.3 pieces and incubated in medium containing S35-methionine (100 uCi/ml.) at 37C under 95% oxygen and 5% carbon dioxide for four hours. The incubated tissues were subjected to two-dimensional electrophoresis and radiofluorography. Over 100 spots were developed in the fluorograms. Three groups of spots, representing cytoskeletal proteins, androgen-dependent proteins and castration-induced proteins, were further evaluated by a computer-based densitometer. The level of densitometry absorption is proportional to the amount of radioactivity in each spot. The synthesis of cytoskeletal proteins, such as actin and tropomyosin, were relatively constant throughout the course of prostatic regression. The rate of synthesis of androgen-dependent proteins declined rapidly from a high level of synthesis before castration to a non-detectable level by Day 3 postcastration. However, three proteins, which were either not synthesized (spot G and spot H) or synthesized at a very low level (spot I) before castration, were the major proteins synthesized by the prostate during early stages of its regression. The rate of synthesis of these proteins reached a peak by Day 4 postcastration, declined rapidly and remained at a low level thereafter. The respective molecular weights and isoelectric points for these three proteins were 33 Kd and 7.2 for spot G, 38 Kd and 5.3 for spot H and 64 Kd and 6.0 for spot I. Previous findings showed that prostatic regression in rats was associated with a surge of activities in proteolytic enzymes which peaked five to six days postcastration. The peak of synthesis of three proteins noted in the present study, therefore, preceded the peak of activities of proteolytic enzymes in the regressing prostate by one to two days. Testosterone replacement to animals at the time of castration prevented the synthesis of these proteins in the prostate. Since the synthesis of these three proteins in the ventral prostate is induced by androgen-depletion resulted from castration, they are considered as the castration-induced proteins.

Secretion of proteins and glycoproteins by perifused rabbit corpus epididymal tubules: effect of castration

Protein synthesis in epididymal tissue of intact and castrated rabbits was studied after incubation of epididymal minces with [35S]-cysteine or [35S]-methionine and protein separation by two-dimensional gel electrophoresis. Regional differences in the pattern of protein synthesized were observed. Castration did not change overall protein synthesis, but it reduced these regional differences. The presence of 5 alpha-DHT in the culture medium of the proximal corpus epididymidis perfused for 24 hr did not increase overall protein synthesis in tubules from intact or castrated rabbits and did not reinitiate synthesis of the proteins that had disappeared after castration. The kinetics of glycoprotein synthesis and secretion were studied by light and electron microscopy autoradiography at 0.5, 2, 6, and 24 hr after exposure to [3H]-mannose, [3H]-fucose, and [3H]-glucosamine. Changes in the distribution of mannose- and glucosamine-labeled material indicated that the decline in grain density over the epithelium from 30 min to 24 hr coincided with an increasing reaction over the stereocilia border from 30 min to 2 hr and in the lumen from 2 to 24 hr. The distribution of fucose-labeled material indicated that the grain reaction over the epithelium declined more rapidly than with the mannose label. When the glucosamine-labeled sperm mass was released from the tubules, the labeled material was lost after the first washing, indicating that the glucosamine-labeled glycoproteins did not bind firmly to corpus spermatozoa within 24 hr. After castration, both mannose- and fucose-labeled materials migrated to the cell apex more rapidly than in the intact animal, but they were not released as readily into the lumen. The culture of epididymal tubules from castrated males with 5 alpha-DHT for 24 hr did not promote the release of either mannose- or fucose-labeled material into the lumen. However, testosterone given in vivo for 2 weeks restored secretion of mannose-labeled material into the lumen.

Effect of "stacking" on the resolving power of ultrathin-layer two-dimensional gel electrophoresis

The resolving power of two-dimensional ultrathin-layer polyacrylamide gel electrophoresis with and without "stacking" was investigated. Side-by-side analysis shows that the use of a properly adjusted upper gel improves the resolution and reproducibility of this sensitive analytical method. The effects of various detergents (Nonidet-P40, Zwittergent, urea) on the ultrathin-layer polyacrylamide gel electrophoresis were also investigated. For this case, whole cell proteins of Pseudomonas aeruginosa and Staphylococcus aureus treated with different detergents were electrofocused in the presence of the same detergents.