Purification and first characterization of the secreted and cellular 52-kDa proteins regulated by estrogens in human-breast cancer cells

An estrogen-regulated 52-kDa glycoprotein secreted by MCF7 breast cancer cells was first purified from serum-free conditioned medium by concanavalin-A--Sepharose (ConA--Sepharose). The 13% pure protein was then used to obtain monoclonal antibodies to the 52-kDa protein [Garcia et al. (1985) Cancer Res. 45, 709-716]. Using ConA--Sepharose and monoclonal antibody affinity chromatographies, the secreted 52-kDa protein was finally purified to homogeneity as verified by silver staining of sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) and one single N-terminal amino acid. The purification factor was approximately 1400 and the yield 40%. The same two-step procedure, applied to MCF7 cell extracts, yielded four immunologically related proteins of 52 kDa, 48 kDa, 34 kDa and 17 kDa, which were purified 1250-fold with a yield of 30%. These components were further separated by high-performance liquid chromatography gel filtration under denaturing conditions. The final products were homogeneous on the basis of silver-stained SDS-PAGE and gel filtration. However, isoelectrofocusing showed that the pI of the secreted 52-kDa protein and the cellular 34-kDa protein varied from 5.5 to 6.5. Amino acid analysis of the secreted and the related cellular 34-kDa protein is given. Western immunoblotting, pulse chase studies and post-translational studies indicate that the 52-kDa protein is the precursors of a lysosomal enzyme which is partially secreted and partially processed into smaller cellular forms.

Hydrophobic adsorbents for the isolation and purification of biosynthetic human growth hormone from crude fermentation mixtures

Hydrophobic interaction chromatography was used as the initial step for the concentration and partial purification of biosynthetic human growth hormone (hGH). This molecule was extracted from the culture medium of a transformed monkey kidney cell line by batch adsorption either to Octyl-Sepharose or Phenyl-Sepharose. The adsorbate was decanted and packed into a column for elution. This initial work-up procedure rendered a concentrated hGH solution that was further purified by ion-exchange and gel filtration chromatography. The hGH obtained was homogeneous, based on polyacrylamide gel electrophoresis, N-terminal sequence and fingerprint analysis.

Purification to homogeneity and NH2-terminal amino acid sequence of a novel interleukin 1 species derived from a human B cell line

A subclone, referred to as 3B6, derived from a DR-negative EBV-transformed B cell line, has been found to spontaneously produce IL 1. 3B6-IL 1 displays a pI of 5 on FPLC chromatofocusing. It has been purified to homogeneity by a sequence of ion-exchange chromatography and affinity chromatography on procion red agarose. The homogeneous material migrated with an apparent m.w. of 13,500 on SDS-PAGE. The overall recovery of IL 1 activity was estimated at 57%. The final material had a specific activity of 7.8 X 10(6) half-maximal units/mg and represented a 50,000-fold purification. A partial NH2-terminal amino acid sequence has been obtained that is different from those reported from monocytic IL 1. However, this molecule can formally be identified as IL 1 on its spectrum of biologic activities. In addition to inducing the proliferation of murine thymocytes in the co-stimulator assay. 3B6-IL 1 is active on both human T and B cells, respectively, in inducing IL 2 synthesis by cells from a subcloned HSB 2 line and promoting the proliferation of anti-IgM-stimulated human peripheral blood B lymphocytes. Furthermore, 3B6-IL 1 acts as a growth factor for normal human fibroblasts and for the 3B6 line itself. However, 3B6-IL 1 is not pyrogenic in rabbits. Thus, the 3B6 cell line was shown to produce a new molecular species of IL 1, with respect to its NH2-terminal sequence, which shared all of the studied biologic activities of monocytic IL 1 except for pyrogenicity.

Purification to homogeneity and NH2-terminal amino acid sequence of a novel interleukin 1 species derived from a human B cell line

A subclone, referred to as 3B6, derived from a DR-negative EBV-transformed B cell line, has been found to spontaneously produce IL 1. 3B6-IL 1 displays a pI of 5 on FPLC chromatofocusing. It has been purified to homogeneity by a sequence of ion-exchange chromatography and affinity chromatography on procion red agarose. The homogeneous material migrated with an apparent m.w. of 13,500 on SDS-PAGE. The overall recovery of IL 1 activity was estimated at 57%. The final material had a specific activity of 7.8 X 10(6) half-maximal units/mg and represented a 50,000-fold purification. A partial NH2-terminal amino acid sequence has been obtained that is different from those reported from monocytic IL 1. However, this molecule can formally be identified as IL 1 on its spectrum of biologic activities. In addition to inducing the proliferation of murine thymocytes in the co-stimulator assay. 3B6-IL 1 is active on both human T and B cells, respectively, in inducing IL 2 synthesis by cells from a subcloned HSB 2 line and promoting the proliferation of anti-IgM-stimulated human peripheral blood B lymphocytes. Furthermore, 3B6-IL 1 acts as a growth factor for normal human fibroblasts and for the 3B6 line itself. However, 3B6-IL 1 is not pyrogenic in rabbits. Thus, the 3B6 cell line was shown to produce a new molecular species of IL 1, with respect to its NH2-terminal sequence, which shared all of the studied biologic activities of monocytic IL 1 except for pyrogenicity.

Influence of food intake on bioavailability of oral 6-mercaptopurine in children with acute lymphoblastic leukemia

Plasma levels of 6-mercaptopurine (6-MP) were measured after oral administration in 17 children with acute lymphoblastic leukemia (ALL). In the fasting state or after a breakfast consisting of 250 ml milk and 50 g biscuits, 6-MP was administered at a dose of 75 mg/m2. In patients studied in a fasting state, the mean time to plasma peak (tmax) level was 1.2 h, whereas in patient studied after breakfast the mean tmax was 2.3 h. This difference is statistically significant (p less than 0.001). Moreover, the 6-MP peak plasma concentration (cmax) and the areas under the plasma concentration time curves (AUC) were significantly reduced when the drug was administered after breakfast. The mean Cmax +/- SD were 0.98 +/- 0.54 microM and 0.63 +/- 0.48 microM, respectively (p less than 0.05). The mean 6-MP AUC +/- SD in patients studied in a fasting state and after breakfast were 143 +/- 69 microM min and 105 +/- 68 microM, respectively (p less than 0.01). These results indicated that 6-MP should be taken in a fasting state to optimize drug absorption in children undergoing chemotherapy for ALL.

Beta-endorphin does not protect alkylation of opiate receptor by N-ethylmaleimide

Rat brain membranes were incubated in N-ethylmaleimide (NEM, 0.5-1.0 mM) in the presence and absence of various concentrations of morphine, Leuenkephalin and human beta-endorphin (beta h-EP). After sufficient washing, the binding of dihydromorphine (DHM), [D-Ala-D-Leu]-enkephalin (DADLE) and tritiated beta h-EP was 10-40% above that of membranes treated with NEM alone. There was no additive effect of morphine and Leu-enkephalin with respect to their effect on recovery of beta h-EP binding. Evaluation of beta h-EP as protecting ligand proved to be difficult since preincubation completely inhibits subsequent DHM and DADLE binding unless a more extensive washing protocol is employed. A protocol for washing beta h-EP preincubated membranes using a Tris-phosphate buffer of pH 6 containing 150 mM NaCl, 20 mM MgCl2 and 10% glycerol was used to recover enough binding potential to evaluate the effects of beta h-EP preincubation towards NEM treatment. Preincubation with beta h-EP itself at 0.1-1.0 microM did not result in any increased recovery of opiate binding, in contrast to the findings with the other two ligands.

Beta-endorphin. Binding activity of synthetic analogs with various chain lengths in neuroblastoma x glioma NG108-15 cell membranes

Inhibition of binding of beta h-endorphin or Leu-enkephalin by beta h-endorphin analogs of various chain lengths in memmbrane preparations of the neuroblastoma x glioma NG108-15 cells has been investigated. The removal of even a single residue from the C-terminus results in the inability of the resulting peptide to completely displace beta h-endorphin. In addition, the proportion of nondisplaceable binding increases with decreasing chain length.

Internal homologies in the two aspartokinase-homoserine dehydrogenases of Escherichia coli K-12

In Escherichia coli, AK I- HDH I and AK II- HDH II are two bifunctional proteins, derived from a common ancestor, that catalyze the first and third reactions of the common pathway leading to threonine and methionine. An extensive amino acid sequence comparison of both molecules reveals two main features on each of them: (i) two segments, each of about 130 amino acids, covering the first one-third of the polypeptide chain, are similar to each other and (ii) two segments, each of about 250 amino acids and covering the COOH-terminal 500 amino acids also present a significant homology. These findings suggest that these two regions may have evolved independently of each other by a process of gene duplication and fusion previous to the appearance of an ancestral aspartokinase-homoserine dehydrogenase molecule.

Structure of the metJBLF cluster in Escherichia coli K12. Sequence of the metB structural gene and of the 5'- and 3'-flanking regions of the metBL operon

The total nucleotide sequence (1,158 nucleotides) of the metB gene of Escherichia coli coding for cystathionine gamma-synthase (386 amino acid residues, Mr = 41,503/chain) is presented. The nucleotide sequences of the flanking regions of the metB and metL genes are also presented. Analysis of these sequences and identification of a promoter region upstream from the metB gene confirms that metB and metL form an operon. The transcription direction is from metB to metL; the start site of the gene transcription has been determined. There is no structural evidence of a classical attenuation mechanism in the regulation of this operon coding for enzymes implicated in an amino acid biosynthetic pathway. Finally, the overall organization of the metJBLF gene cluster is discussed.

Appendix. Purification, molecular weight, and NH2-terminal sequence of cystathionine gamma-synthase of Escherichia coli

The cystathionine gamma-synthase of Escherichia coli has been purified to homogeneity. It is a tetramer (Mr = 160,000) composed of identical subunits (Mr approximately 40,000). We have determined its amino acid terminal sequence and thus localized the starting codon of the metB structural gene.

Nucleotide sequence of metF, the E. coli structural gene for 5-10 methylene tetrahydrofolate reductase and of its control region

The nucleotide sequence of the E.coli metF gene (888 nucleotides), coding for 5-10 methylene tetrahydrofolate reductase, has been determined. The metF gene product was identified in maxicells and found to be a protein of subunit molecular weight 33,000, in agreement with the size of the coding region. The starting point for metF transcription was determined by S1 nuclease mapping. No structural evidence was found for an attenuation mechanism regulating the independent metF transcriptional unit. Comparison of the regulatory region preceding the metF structural gene with the 5' flanking region of the metBL operon shows some homology spanning 24 nucleotides. These homologous sequences could be operator structures belonging to the two transcriptional units, metF and metBL, and recognized by the same regulatory protein.

[Submicroscopic study of brown adipose tissue in young rats by the freeze-fracturing method]

The authors report the results of their ultrastructural study on the rat brown adipose tissue using the freeze-fracturing techniques. It is well known from transmission electron microscopy that lipid vacuoles of the brown adipose tissue cells are bound by a dense line corresponding to a structure as yet totally unknown. The results of the study using freeze-fracturing technics show that the morphology of lipid vacuoles surface is different from that of the typical unit membrane. The possibility is discussed that the particular aspect of the surface is due to the lypolysis induced by tissue fixation.

Synthesis and properties of beta h-endorphin analogs containing the dynorphin-(1-13) sequence

Two analogs of beta h-endorphin containing dynorphin-(5-13) or dynorphin-(6-13) sequence have been synthesized by the solid-phase method. Biological activities of the analogs have also been investigated. It was found that the opiate activity is about three times more than beta h-endorphin in the guinea pig ileum assay. Both analgesic potency and opiate receptor-binding activity of the analogs are lower when compared with beta h-endorphin. However, the analogs have interesting behavioral effects in mice.

Construction and physical mapping of plasmids containing the metJBLF gene cluster of E. coli K12

In vitro recombination techniques were used to clone the E. coli metJBLF gene cluster in a plasmid vector. Several chimeric plasmids were obtained, analyzed by restriction mapping and characterized genetically. The combined results establish that the met gene cluster is contained on an approximately 5.6 kilobase segment of bacterial DNA with metL between metB and metF. The origin of metL was localized precisely by its DNA sequence and its transcription direction was established.

Beta-Endorphin. Interaction of synthetic analogs having different chain lengths with morphine and enkephalin receptors in rat brain membranes

Human beta-endorphin analogs with various chain lengths have been investigated for their potency in displacing tritiated dihydromorphine and Leu-enkephalin binding in rat brain membrane preparations. It was found that the reduction of chain length from residues 1-31 to 1-5 led to a gradual loss of preference for the morphined receptor. In addition, the extension of the chain length of the Met-ekephalin segment to the COOH-terminal glutamic acid modified the binding of the NH2-terminal sequence to the enkephalin receptor. The fact that camel beta-endorphin is more potent in displacing the two tritiated primary ligands than the human hormone is also reported herein.

Synthesis and properties of human growth hormone fragments

The solid phase synthesis of fragments 75-120-NH2 and 73-128-GlyNH2 of the human growth hormone sequence is described. Purification was by solvent extraction, gel filtration and partition chromatography. No growth-promoting activity was detected in any of the peptides by the rat body-growth assay. An immunochemically reactive area was located in the sequence 73-128 when tested by complement fixation assays.

Opiate receptor-binding activity of [D-Thr2,Thz5]-and [D-Met2,Thz5]-enkephalinamides

The binding characteristics of two highly potent analgesic enkephalin analogs, [D-Thr2, Thz5]-and [D-Met2, Thz5]-enkephalinamide, to the rat brain membrane preparation have been investigated using tritiated Leu-enkephalin, human beta-endorphin or dihydromorphine as the primary ligand. Concentrations for 50% inhibiting activity of the enkephalin analogs are much lower in displacing tritiated dihydromorphine in comparison with that for the other two tritiated ligands. In addition, a correlation between analgesic potency and capacity to displace tritiated dihydromorphine is observed. These data may explain the high antinociceptive activity of the enkephalin analogs and support the hypothesis that the mu-receptor is involved with analgesia.

beta-Endorphin: characteristics of binding sites in a neuroblastoma--glioma hybrid cell

Specific binding of human beta-endorphin to NG108-15 cells is described; human beta-[Tyr27-3H2] endorphin was used as the ligand. The binding is time dependent and saturable; Kd = 0.3 nM and ka = 1.8 x 10(8) M-1 min-1. Under the conditions optimal for beta-endorphin binding, leucine-enkephalin has one-fourth to one-third as many binding sites as beta-endorphin and its affinity is 7--10% that of beta-endorphin. Monovalent and divalent cations potently inhibit binding. Trypsin, phospholipase A, and N-ethylmaleimide reduce the ability of NG108-15 cells to bind beta-endorphin. beta-Endorphin analogs are able to fully inhibit the binding of beta-[Tyr27-3H2]endorphin, although enkephalins, morphine, and naloxone inhibit only 50--80%.

Beta-endorphin: synthesis and radioligand binding activity of analogs containing cystine bridges

Two analogs of human beta-endorphin containing cystine bridges between positions 21 and 26 or 14 and 26 have been synthesized and their radioligand binding activity using rat brain membranes has been determined. Both peptides showed three to four times the binding activity of human beta-endorphin.

beta-Endorphin: characteristics of binding sites in rabbit spinal cord

The interaction of human beta-endorphin with binding sites in rabbit spinal cord has been characterized. The stereospecific high-affinity binding sites are concentrated in the dorsal half of the spinal cord. Scatchard analysis of the binding data shows heterogeneity of the binding sites that can be resolved into two populations with apparent dissociation constants of 3.0 (+/-2.0) X 10(-10) and 3.3 (+/- 0.5) X 10(-9) M. Sodium ions decrease the binding of human beta-endorphin to spinal cord to the same extent as found in rat brain. The ability of several opiates and opioid peptides to inhibit the binding of human beta-endorphin is also presented.

beta-Endorphin: radioreceptor binding assay. Relative potency of synthetic analogs with various chain lengths

An assay system is described to measure the specific binding of beta-endorphin to opiate sites (receptors) in rat brain membrane preparations using the tritiated hormone as the primary ligand. By this assay procedure, the radioreceptor activity of beta-endorphin and synthetic analogs with various chain lengths has been determined. The results suggest that both NH2- and COOH-terminal sequences of the molecule are involved in the interaction of beta-endorphin with opiate receptors.