Cell surface localization of the peripheral-type benzodiazepine receptor (PBR) in adrenal cortex

Previous studies demonstrated that the mitochondrial peripheral-type benzodiazepine receptor (PBR) regulates steroid biosynthesis. In this study we investigate further PBR action by examining its subcellular localization in mouse adrenal gland using anti-peptide PBR antiserum and employing biotin-streptavidin peroxidase immunocytochemistry. Results demonstrated PBR immunostaining exclusively in the cortex. Within this region, however, PBR staining was homogeneously distributed in cells of the zona glomerulosa, whereas in cells of the zona fasciculata both cytoplasmic and prominent plasma membrane immunostaining was evident. Next, PBR distribution was examined using confocal microscopy. Confocal optical sections were obtained, 3-D reconstructions of these sections generated, and vertical, z-sections of the 3-D reconstruction recreated. The immunostaining pattern observed was consistent with a cell surface distribution of PBR. The demonstration of a subset of PBR at the plasma membrane may account for actions of PBR ligands not related to mitochondrial function.

High-dose folinic acid and 5-fluorouracil plus cisplatin on a weekly schedule in the treatment of advanced cancer of the head and neck

A group of 60 patients with advanced head/neck cancer were treated with high-dose folinic acid (500 mg/m-2/week-1) plus 5-fluorouracil (400 mg/m-2/week-1 on day 1, and cisplatin (20 mg/m-2/week-1) 24 h after folinic acid infusion was completed. Out of 55 evaluable patients, 10 patients (18%) experienced a complete response with a mean duration of 11.4+ months, 25 patients had a partial response (45%) of 6.7+ months, 6 patients (11%) showed a stabilization of 4.8+ months, and 14 (25%) progressed. The overall response rate was 63.6% (95% confidence limits 56.5%-69.5%). Patients pretreated with radiotherapy had a 67% overall response rate, while those pretreated with chemotherapy showed a 54% overall response rate. All patients with cancer of the oropharynx had a major response, while patients with cancer of the oral cavity had the lowest response rate. The mean survival of patients who attained a complete response was 14.5+ months. Partial responders had a mean survival of 10.6+ months, while patients who progresses survived a mean of 3.6+ months. The treatment has been very well tolerated with few cases of grade 3 gastrointestinal toxicity. Grade 1-2 leukopenia was recorded in 64% of cases, grade 1-2 nausea/vomiting in 85%. In one case therapy was stopped because of persistent diarrhoea.

Hemopexin is synthesized in peripheral nerves but not in central nervous system and accumulates after axotomy

In adult mammals, injured axons regrow over long distances in peripheral nerves but fail to do so in the central nervous system. Analysis of molecular components of tissue environments that allow axonal regrowth revealed a dramatic increase in the level of hemopexin, a heme-transporting protein, in long-term axotomized peripheral nerve. In contrast, hemopexin did not accumulate in lesioned optic nerve. Sciatic nerve and skeletal muscle, but not brain, were shown to be sites of synthesis of hemopexin. Thus, hemopexin expression, which can no longer be considered to be liver-specific, correlates with tissular permissivity for axonal regeneration.

In-gel digestion of proteins for internal sequence analysis after one- or two-dimensional gel electrophoresis

We examined the different steps necessary for the enzymatic digestion of proteins in the polyacrylamide matrix after gel electrophoresis. As a result, we developed an improved method for obtaining peptides for internal sequence analysis from 1-2 micrograms of in-gel-digested proteins. The long washing-lyophilization-equilibration steps necessary to eliminate the dye, sodium dodecyl sulfate, and other gel-associated contaminants that perturb protein digestion in Coomassie blue-stained gels have been replaced by washing for 40 min with 50% acetonitrile, drying for 10 min at room temperature, and then rehydrating with a protease solution. The washing and drying steps result in a substantial reduction of the gel slice volume that, when next swollen in the protease solution, readily absorbs the enzyme, facilitating digestion. The Coomassie blue staining procedure has also been modified by reducing acetic acid and methanol concentrations in the staining solution and by eliminating acetic acid in the destaining solution. The peptides resulting from the in-gel digestion are easily recovered by passive elution, in excellent yields for structural characterization. This simple and rapid method has been successfully applied for the internal sequence analysis of membrane proteins from the rat mitochondria resolved in preparative two-dimensional gel electrophoresis.

A member of the tetra spans transmembrane protein superfamily is recognized by a monoclonal antibody raised against an HLA class I-deficient, lymphokine-activated killer-susceptible, B lymphocyte line. Cloning and preliminary functional studies

The IA4 mAb was identified among a series of antibodies raised in BALB/c mice after immunization against a HLA class I-deficient, lymphokine-activated killer (LAK)-susceptible EBV-B lymphocyte line. The IA4 antibody was selected because of its high expression, in the range of 10(5) to 25 x 10(5) sites/cell, on several B lymphocyte lines (EBV-transformed or Burkitt) and monocytic lines such as HL60 and U937, and because its expression was correlated with both target susceptibility to LAK lysis and reduced expression of HLA class I surface Ag on two pairs of EBV-B-transformed cell lines (721/721.134 and MM/10F2). Despite the strategy followed to raise the mAb and the correlation mentioned above, no direct role of the IA4 molecules in LAK susceptibility has been established, since the IA4 molecule is poorly expressed on the sensitive targets Daudi and K562; moreover, the IA4 antibody did not affect reproducibly the in vitro killing of positive target cells by LAK effectors. The IA4 antibody was poorly immunoprecipitating and the surface molecule recognized was identified by gene cloning following an expression strategy using a U937 cDNA library transfected in COS cells, and a screening strategy based on membrane expression of IA4 molecule. The IA4 cDNA is virtually identical to "R2," a mRNA species previously identified in activated human T cells by subtractive hybridization. The IA4 cDNA contains an open reading frame coding for a protein 267 amino acids long with four potential transmembrane domains and one large external hydrophilic domain of about 110 amino acids, possibly glycosylated. The encoded protein belongs to a family of surface molecules, the tetra spans transmembrane protein superfamily, all displaying the four transmembrane domains, expressed on various cell types including lymphocytes (CD9, CD37, CD53, TAPA-1), melanoma cells (ME491), and intestinal cells (CO-029). These molecules have been reported to be involved in cell activation and cell death. Surprisingly, the Schistosoma mansoni Ag Sm23 displays significant homologies with this family. The IA4 molecule is a widely distributed surface marker expressed on circulating lymphocytes and monocytes, newborn thymocytes, and the cell lines mentioned above. The IA4 molecule expression is up-regulated upon cell activation. Weakly expressed on resting peripheral T and B lymphocytes and large granular lymphocytes (NK), its expression roughly doubles after activation by PHA, staphylococcus aureus Cowan I, and IL-2, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

A member of the tetra spans transmembrane protein superfamily is recognized by a monoclonal antibody raised against an HLA class I-deficient, lymphokine-activated killer-susceptible, B lymphocyte line. Cloning and preliminary functional studies

The IA4 mAb was identified among a series of antibodies raised in BALB/c mice after immunization against a HLA class I-deficient, lymphokine-activated killer (LAK)-susceptible EBV-B lymphocyte line. The IA4 antibody was selected because of its high expression, in the range of 10(5) to 25 x 10(5) sites/cell, on several B lymphocyte lines (EBV-transformed or Burkitt) and monocytic lines such as HL60 and U937, and because its expression was correlated with both target susceptibility to LAK lysis and reduced expression of HLA class I surface Ag on two pairs of EBV-B-transformed cell lines (721/721.134 and MM/10F2). Despite the strategy followed to raise the mAb and the correlation mentioned above, no direct role of the IA4 molecules in LAK susceptibility has been established, since the IA4 molecule is poorly expressed on the sensitive targets Daudi and K562; moreover, the IA4 antibody did not affect reproducibly the in vitro killing of positive target cells by LAK effectors. The IA4 antibody was poorly immunoprecipitating and the surface molecule recognized was identified by gene cloning following an expression strategy using a U937 cDNA library transfected in COS cells, and a screening strategy based on membrane expression of IA4 molecule. The IA4 cDNA is virtually identical to "R2," a mRNA species previously identified in activated human T cells by subtractive hybridization. The IA4 cDNA contains an open reading frame coding for a protein 267 amino acids long with four potential transmembrane domains and one large external hydrophilic domain of about 110 amino acids, possibly glycosylated. The encoded protein belongs to a family of surface molecules, the tetra spans transmembrane protein superfamily, all displaying the four transmembrane domains, expressed on various cell types including lymphocytes (CD9, CD37, CD53, TAPA-1), melanoma cells (ME491), and intestinal cells (CO-029). These molecules have been reported to be involved in cell activation and cell death. Surprisingly, the Schistosoma mansoni Ag Sm23 displays significant homologies with this family. The IA4 molecule is a widely distributed surface marker expressed on circulating lymphocytes and monocytes, newborn thymocytes, and the cell lines mentioned above. The IA4 molecule expression is up-regulated upon cell activation. Weakly expressed on resting peripheral T and B lymphocytes and large granular lymphocytes (NK), its expression roughly doubles after activation by PHA, staphylococcus aureus Cowan I, and IL-2, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Cloning and expression in Escherichia coli of the gene encoding Aspergillus flavus urate oxidase

Amino acid sequencing of peptides obtained after proteolytic hydrolysis of Aspergillus flavus urate oxidase (uricase) permitted the design of oligodeoxynucleotide probes that were used to obtain 1.2- and 5-kilobase pair DNA fragments from A. flavus cDNA and genomic libraries, respectively. The cDNA fragment contained the entire coding region for uricase, and comparison with the genomic fragment revealed the presence of two short introns in the coding region of the gene. A. flavus uricase has around 40% overall identity with uricases from higher organisms but with many conserved amino acids. Hitherto highly conserved consensus patterns found in other uricases were found to be modified in the A. flavus enzyme, notably the sequence Val-Leu-Lys-Thr-Thr-Gln-Ser near position 150, which in the filamentous fungus is uniquely modified to Val-Leu-Lys-Ser-Thr-Asn-Ser. Silent mutations were introduced by cassette mutagenesis near the 5'-extremity of the coding sequence in order to conform with Escherichia coli codon usage, and the uricase was expressed in the E. coli cytoplasm in a completely soluble, biologically active form.

Clustering proteins into families using artificial neural networks

An artificial neural network was used to cluster proteins into families. The network, composed of 7 x 7 neurons, was trained with the Kohonen unsupervised learning algorithm using, as inputs, matrix patterns derived from the bipeptide composition of 447 proteins, belonging to 13 different families. As a result of the training, and without any a priori indication of the number or composition of the expected families, the network self-organized the activation of its neurons into topologically ordered maps in which almost all the proteins (96.7%) were correctly clustered into the corresponding families. In a second computational experiment, a similar network was trained with one family of the previous learning set (76 cytochrome c sequences). The new neural map clustered these proteins into 25 different neurons (five in the first experiment), wherein phylogenetically related sequences were positioned close to each other. This result shows that the network can adapt the clustering resolution to the complexity of the learning set, a useful feature when working with an unknown number of clusters. Although the learning stage is time consuming, once the topological map is obtained, the classification of new proteins is very fast. Altogether, our results suggest that this novel approach may be a useful tool to organize the search for homologies in large macromolecular databases.

Expression and pharmacological characterization of the human peripheral-type benzodiazepine receptor in yeast

Recently we cloned the cDNA coding for the putative human peripheral-type benzodiazepine receptor (hPBR). This report describes the expression of this cDNA in Saccharomyces cerevisiae and the characterization of the recombinant protein. The expression was achieved by placing the receptor cDNA under the control of a galactose-regulated artificial promoter. After galactose induction, the transformed cells expressed a functional hPBR which displayed a Kd for the specific peripheral-type ligand [3H]PK11195 of 9.9 +/- 1.3 nM and a maximal binding capacity of 249,300 +/- 50,400 sites/cell. The pharmacological characterization of the recombinant receptor, determined in competitive ligand binding experiments, agrees closely with that described for the natural receptor expressed by human cells. Furthermore, the binding was stereospecific as shown by the displacement of the [3H]PK11195 binding by PK14067 (-Q1) and not by PK14068 (+Q1). Photolabeling experiments showed that transformed cells expressed a 18 kDa protein which was specifically labeled with [3H]PK14105. Altogether these results show that the cDNA transfected in yeast encodes a 18 kDa protein with the expected characteristics of the hPBR.

Role of interleukin 6 in the inflammatory response after cataract surgery. An experimental and clinical study

The mechanism of uveitis following cataract surgery, which is mediated in part by the cyclooxygenase pathway, is complex, the complexity of which is likely to be due to several factors. We investigated the possible local involvement of interleukin 6 (IL-6) in this response. Using a specific bioassay, we showed a dramatic increase of IL-6 levels (> 4 x 10(3) times) in all of the aqueous humors of 12 patients following cataract surgery. The IL-6 levels in serum samples were below detection limits, indicating a local production of this cytokine. In addition, the injection of highly purified recombinant interleukin 6 in the anterior chamber of the eye in rabbits resulted in an inflammatory response. These observations suggest that IL-6 may play a crucial role in the occurrence of inflammation after cataract surgery, and it may lead to new therapeutic approaches to this problem.

Isolation, purification and primary structure of insulin from the turtle Chrysemys dorbigni

Insulin A and B chains from pancreas of the turtle Chrysemys dorbigni have been purified to homogeneity, and their primary structures have been determined. The sequence of the A chain is G-I-V-E-Q-C-C-H-N-T-C-S-L-Y-Q-L-E-N-Y-C-N, and that of the B chain is A-A-N-Q-H-L-C-G-S-H-L-V-E-A-L-Y-L-V-C-G-E-R-G-F-F-Y-S-P-K-A. The amino acid sequence of Chrysemys insulin is identical to that of another turtle (Pseudemys scripta), the chicken, and turkey. When compared with alligator insulin, it has three conservative substitutions in the B chain. However, there are seven substitutions when compared with the insulin of the rattlesnake.

Structure-function study of the p55 subunit of murine IL-2 receptor by epitope mapping

Using a cell-free translation system we have expressed the Mr 55,000 subunit of the murine IL-2R (p55 IL-2R), which binds IL-2 with low affinity (Kd = 10 nM). Mutants and truncated forms of p55 IL-2R have been used to map the epitopes recognized by three anti-p55 IL-2R mAb: 135D5, 7D4, and 2E4. The mAb 135D5 inhibits IL-2 binding to p55 IL-2R and recognizes an epitope located between amino acids 64 to 125. This epitope can be mimicked by a synthetic peptide corresponding to the region defined by residues 72 to 88. However, the mAb 7D4 and 2E4 do not affect the IL-2 binding to p55 IL-2R. These mAb recognize an epitope of p55 IL-2R lying between residues 125 to 212 that can be mimicked with a peptide corresponding to amino acids 188 to 208. A strong correlation emerged between the experimental results on epitope mapping and predictions of potential antigenicity of murine p55 IL-2R. In addition, we described two internal initiation sites of p55 IL-2R mRNA under the in vitro conditions used leading to the production of significant amounts of N-terminal truncated p55 IL-2R proteins.

Structure-function study of the p55 subunit of murine IL-2 receptor by epitope mapping

Using a cell-free translation system we have expressed the Mr 55,000 subunit of the murine IL-2R (p55 IL-2R), which binds IL-2 with low affinity (Kd = 10 nM). Mutants and truncated forms of p55 IL-2R have been used to map the epitopes recognized by three anti-p55 IL-2R mAb: 135D5, 7D4, and 2E4. The mAb 135D5 inhibits IL-2 binding to p55 IL-2R and recognizes an epitope located between amino acids 64 to 125. This epitope can be mimicked by a synthetic peptide corresponding to the region defined by residues 72 to 88. However, the mAb 7D4 and 2E4 do not affect the IL-2 binding to p55 IL-2R. These mAb recognize an epitope of p55 IL-2R lying between residues 125 to 212 that can be mimicked with a peptide corresponding to amino acids 188 to 208. A strong correlation emerged between the experimental results on epitope mapping and predictions of potential antigenicity of murine p55 IL-2R. In addition, we described two internal initiation sites of p55 IL-2R mRNA under the in vitro conditions used leading to the production of significant amounts of N-terminal truncated p55 IL-2R proteins.

Human recombinant dimeric IL-6 binds to its receptor as detected by anti-IL-6 monoclonal antibodies

Three different epitopes of the human IL-6 (IL-6) molecule were recognized by the mAb B-E4 (IgG2b), B-E8 (IgG1) and B-F6 (IgG1). The affinities of these three mAb for IL-6 differ little in several assays but if ranked by affinity they fall into the following order B-E8 greater than B-E4 greater than B-F6. B-E4 and B-E8 mAb, recognizing two different epitopes, are inhibiting mAb in the bioassay with the IL-6 depending cell line B9, however B-E8 has an inhibiting activity higher than B-E4. Both human natural IL-6 (HnIL-6) and human recombinant IL-6 (HrIL-6) were inhibited but not the murine natural IL-6 (MnIL-6). Surprisingly, not only the non-inhibiting mAb (B-F6) recognizes the HrIL-6 fixed to the receptor but also the inhibiting mAb B-E4 and B-E8. This together with the results obtained in a sandwich ELISA where the same mAb was used as both catcher and tracer to detect HrIL-6, it was concluded that dimeric HrIL-6 is able to fix the IL-6 receptor. Competition studies between monomeric HnIL-6 and dimeric HrIL-6 showed that the affinity of the dimeric HrIL-6 for the receptor was higher than that of HnIL-6.

Cloning and sequencing of PYBP, a pyrimidine-rich specific single strand DNA-binding protein

In the human transferrin gene promoter, PRI and DRI are positive cis-acting elements interacting respectively with two families of proteins, Tf-LF1 and Tf-LF2. In this paper, we report the purification from rat liver nuclei, of one of these factors, PYBP, as well as the cloning and the sequencing of its cDNA. PYBP is a DNA-binding protein, purified as a 58 kDa doublet which binds only to single strand pyrimidine-rich DNA present for example in PRI and DRI. The protein binds also to a similar polypyrimidine tract present in one of the two strands of a DNA regulatory element of the rat tyrosine aminotransferase gene enhancer. PYBP gene is transcribed ubiquitously as a roughly 2.8 kb RNA which is likely to be subject to an alternative splicing. PYBP is highly homologous to a mouse nuclear protein, as well as to PTB, its human version, which interacts specifically with the pyrimidine tracts of introns. Primary structure information and predicted secondary structure elements of the protein indicate that PYBP contains four sequence repeats. Each of these repeats appears to exhibit the typical RNA recognition motif found in several proteins interacting with RNA or single strand DNA. Finally several hypotheses concerning the biological function of PYBP are presented.

Primary structure of alpaca growth hormone

Reduced and carbamidomethylated alpaca growth hormone was submitted to tryptic digestion. Peptides in the mixture were purified by reverse phase HPLC and N-terminal determination and an amino acid analysis of each was performed. Data obtained and the already known primary structure of the equine growth hormone allowed the assembly-by homology-of a definite sequence of amino acids for the polypeptide chain of the protein. Present data provide further information about the relationship between growth factors.

Molecular cloning and chromosomal localization of a human peripheral-type benzodiazepine receptor

The sequencing of endopeptidase-generated peptides from the peripheral binding site (PBS) for benzodiazepines, purified from a Chinese hamster ovary (CHO) cell line, produced internal sequence information, and confirmed and extended the NH2-terminal PBS sequence that we previously reported. Since the sequences were highly similar to the corresponding rat PBS sequences, we investigated whether they were also conserved in human PBS. Scatchard analysis of [3H]PK11195 (a derivative of isoquinoline carboxamide) binding and photoaffinity labeling with [3H]PK14105 (a nitrophenyl derivative of PK11195) revealed that CHO PBS and human PBS are closely related. Furthermore a rabbit antiserum raised against three peptides synthesized on the basis of the CHO PBS sequence immunoprecipitate the solubilized U937 PBS and also recognize the human protein in an immunoblot analysis. Based on these results, we screened a U937 cell cDNA library with four oligonucleotide probes derived from the CHO sequence. Two of the probes hybridized with several clones that we isolated and sequenced. One of these, h-pPBS11, is 831 nucleotides and contains a full-length representation of human PBS mRNA. The amino acid sequence of human PBS deduced from the cDNA is 79% identical to that reported for rat PBS, however, human PBS contains two cysteines while rat PBS is characterized by the absence of this amino acid. Using the cDNA of human PBS as a probe, the PBS gene was located in the 22q13.3 band of the human genome.

Human interleukin 1 beta fused to the human growth hormone signal peptide is N-glycosylated and secreted by Chinese hamster ovary cells

A hybrid gene consisting of the sequences coding for the signal peptide of human growth hormone and the mature form of interleukin-1 beta (IL-1 beta) was chemically synthesized. This sequence was inserted into a eukaryotic expression vector and introduced into Chinese hamster ovary cells. The resulting stably transformed cell lines produced large amounts of recombinant IL-1 beta, which was secreted into the culture medium mainly as a 22-kDa form. Expression in the presence of tunicamycin, an inhibitor of N-glycosylation, led to the complete disappearance of the 22-kDa form and the appearance of a new form of 17.5 kDa, indicating that the hybrid protein had been both processed and N-glycosylated. However, transformed cells producing mature IL-1 beta without a signal peptide produced the predicted 17.5-kDa nonglycosylated form. These results suggest that fusion to a heterologous leader sequence allowed IL-1 beta to be translocated across the membrane of the endoplasmic reticulum and to be transported and secreted by the exocytotic pathway.

[Comparative evaluation of echography, computerized tomography and magnetic resonance imaging in the diagnosis of hepatocellular carcinoma in cirrhotic patients]

The contribution of US, CT, and MR imaging was investigated in 25 cirrhotic patients with hepatocellular carcinoma. The following parameters were considered: lesion detection, site and size of the lesion, daughter nodules, location and/or infiltration of intrahepatic vessels, patency of portal vein and collateral vessels, signs of chronic liver disease, steatosis, ascitis, and lymphadenopathy. Our results confirm the value of US, which also allowed lesion biopsy in all cases. CT was as accurate as US in detecting the lesion and even superior in demonstrating daughter nodules. MR imaging, with conventional SE and IR sequences, was inferior since it missed 3 lesions due to motion artifacts; moreover, a smaller number of daughter nodules was seen than with CT. The authors conclude that, at present, MR imaging cannot replace US and CT; the latter, if combined with arteriography, using either hydrosoluble or liposoluble contrast agents, gives the best results in the detection of small hepatocellular carcinomas, and especially of daughter nodules which are important factors for planning appropriate therapy.

Low dose aprotinin as blood saver in open heart surgery

Bleeding after open heart surgery is still a great concern for the surgeon, especially when the surgical field has been revised accurately and hemostatic stitches and electrical cauterization have been used extensively. Among non-surgical adjuncts, aprotinin has been reported as very effective in reducing complications. At the time we started using this drug, we intended to test two different dosages lower than those reported in the literature. We evaluated three groups of 18 patients: the first (A) received about 350 mg of aprotinin from the start of anesthesia up to the end of operation (140 mg in the priming of cardio-pulmonary bypass and 70 mg/h i.v. during the procedure; the second (A/2) received half that dose (i.e. 70 mg and 35 mg, respectively), and the third (C) did not receive aprotinin. We compared in these groups: postoperative bleeding, blood transfusions, red blood cells, hemoglobin, hematocrit, platelets. The results were good only in the A group: bleeding was reduced and few transfusions were required. The patients in the A/2 and C groups did not show significant differences. From our observations we conclude that aprotinin is a useful adjunct, but has to be given in the proper dose.

Relationship between the antigenic topography and the structure of human growth hormone

Monoclonal antibodies (MAb) to human GH (hGH) were used to correlate the antigenic topography of the hormone with its structure. Competition experiments performed in a solid phase RIA system allowed us to measure the reactivity toward the MAb of the following hGH derivatives: hGH 20K (a natural variant lacking residues 32-46), hGH selectively modified in His or Met residues, hGH with the C and/or N-terminal disulfide bond reduced and carbamidomethylated, and hGH cleaved between residues 142-143. Results indicated that fragment 32-46 participates in the structure of epitopes EB1/EB3 and that the C-terminal bridge is located in epitope 10D6, whereas opening of both disulfide bridges alters the entire hGH antigenic surface. His-151 and Met-170 were placed in epitopes NA71 and AC8, respectively, whereas His-18 and Met-14 would be involved in the hGH antigenic domain formed by overlapping epitopes 3C11, 10C1, and HG3. MAb AE5, AE12, and AC3 define a flexible hGH region related to sequence 134-150; the respective epitopes show high conformational mobility induced by modifications in other regions of the molecule. Binding of the different hGH derivatives to lactogenic receptors from female rat liver gave some insights on the localization of the hormone-binding site. Epitopes EB1/EB3 and 10D6 were discarded because there was not a direct correlation between their drastic immunological alterations and the binding properties of the respective hGH derivatives. In the same way, epitopes AE5, AE12, and AC3 were excluded from the hGH-binding domain because a disruption in those sites did not affect the hGH interaction with receptors. We conclude that the hGH structure defined by epitopes 3C11, 10C1, and HG3 is probably related to the binding properties of the hormone.

A new extra sequence at the amino terminal of a mu heavy chain disease protein (DAG)

The primary structure of a human mu heavy chain (DAG) protein is described. The native protein is a circular decamer with a molecular weight (Mr) of 500 kDa, each decamer being constituted of the constant domains C mu 2, C mu 3 and C mu4 and interlinked by 15 disulfide bridges. At its NH2-terminal each monomeric chain starts with an "extra sequence". The amino acid sequence of this segment is Arg-Gln-Ser-Asp-Asp-Pro-Val-Leu-Arg-Gly-Thr-Thr-Val-Pro-Val-Thr-Glu and its reinitiation point is located at Val223 (Gal numbering), at the beginning of C mu 2. This sequence has no homology with any other protein included in the present databases.

Separation by cation-exchange high-performance liquid chromatography of three forms of Chinese hamster ovary cell-derived recombinant human interleukin-2

Purified recombinant (r) interleukin 2 (IL-2) produced by a transformed Chinese hamster ovary cell line shows a single peak when analysed by reversed-phase high-performance liquid chromatography, but it can be resolved into three forms by sodium dodecyl sulphate polyacrylamide gel electrophoresis. These three forms were successfully isolated by narrow-bore ion-exchange chromatography through optimization of the elution conditions. The addition of n-propanol as an organic modifier to the mobile phase proved to be essential for the recovery of the protein from the column in a yield of 90% or better based on protein quantification and biological activity determination. This chromatographic method was used for the purification of these three rIL-2 forms which represent variable glycosylation of a single polypeptide chain. A comparison of the biological activities using the murine CTLL-2 cell proliferation assay showed that the specific activities of the three forms are similar.