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G Goldberger

Publications and source records attributed to G Goldberger.

28 records · Page 2Linked to original sources
PubMed1983

Intracellular and extracellular processing of human apolipoprotein A-I: secreted apolipoprotein A-I isoprotein 2 is a propeptide.

We have recently proposed that the major secreted isoprotein form of human apolipoprotein A-I (designated apo A-I2) is modified extracellularly to become the predominant apo A-I form seen in plasma (designated apo A-I4). In the current report we demonstrate that the primary translation product of human apo A-I (designated apo A-I2p) has a 24-amino-acid NH2-terminal extension with a sequence of Met-Lys-Ala-Ala-Val-Leu-Thr-Leu-Ala-Val-Leu-Phe- Leu-Thr-Gly-Ser-Gln-Ala-Arg-His-Phe-Trp-Gln-Gln. The first 18 amino acids of this NH2-terminal extension are cleaved intracellularly by the signal peptidase, resulting in the formation of apo A-I2, which is the secreted form of apo A-I. Sequence analysis of apo A-I2 confirmed that it contains a hexapeptide extension at its NH2 terminus compared to apo A-I4. This observation demonstrates that apo A-I2 is a propeptide and that the apo A-I2 to apo A-I4 conversion involves the removal of the NH2-terminal hexapeptide of apo A-I2 by a protease in plasma, lymph, or both. Our findings indicate that apo A-I is synthesized as a prepropeptide, which undergoes intracellular and extracellular proteolysis to attain the major plasma apo A-I4 isoprotein form.

Amino Acid Sequence↗
PubMed1983

Biosynthesis and postsynthetic processing of human C-reactive protein.

Human C-reactive protein (CRP) is one of several plasma proteins that increase after tissue injury or inflammation. The magnitude of the increase in CRP (100 to 1000-fold over the resting state) makes this an excellent model for studies of eukaryotic gene control. Accordingly, the biosynthesis and postsynthetic processing of human CRP was examined under cellfree conditions and in Xenopus oocytes injected with liver mRNA. The primary translation product is larger than native serum CRP by an 18-amino acid amino terminal extension. The sequence of this signal peptide was derived from nucleotide sequencing of a 1.8-kilobase (Kb) CRP-specific cDNA clone. Northern blot analysis revealed a CRP mRNA of approximately 2.2 Kb, a size more than three times that required (615 bases) to code for the primary translation product. These data form the basis for study of molecular control of the acute phase response.

Amino Acid Sequence↗
PubMed1982

Complement proteins C2, C4 and factor B. Effect of glycosylation on their secretion and catabolism.

Tunicamycin, an inhibitor of N-acetylglucosaminylpyrophosphopolyisoprenol-dependent glycosylation, was used to study the effect of glycosylation on the synthesis, post-translational modification, secretion and function of the complement proteins that are associated with the major histocompatibility complex in humans, mice and guinea pigs. Tunicamycin blocked glycosylation of pro-C4, C2 and factor B and inhibited secretion of the corresponding native complement proteins synthesized by guinea-pig peritoneal macrophages in tissue culture. In addition, underglycosylated pro-C4 was more rapidly catabolized intracellularly than the corresponding fully glycosylated pro-complement protein. C4 protein secreted by cells incubated with tunicamycin had approximately the same specific biological activity as the protein obtained from control culture media, suggesting that carbohydrate is not required for its activity in immune haemolysis. Direct studies of carbohydrate incorporation and the tunicamycin effect suggested an unequal distribution of sugar among the C4 subunits, with maximal incorporation of carbohydrate into alpha-, and less into the beta-chain of the native protein.

Animals↗
PubMed1982

Biosynthesis and processing of a human precursor complement protein, pro-C3, in a hepatoma-derived cell line.

A 180,000-dalton single-chain molecule (human pro-C3) is the precursor of the third component of human complement (C3), a disulfide-linked two-chain protein. The pro-C3 is converted by limited proteolysis to C3. The relationship between pro-C3 and C3 was established with the use of Hep G2, a cell line derived from a human hepatocellular carcinoma, which synthesizes at least 17 plasma proteins.

Animals↗
PubMed1982

Isolation of cDNA clones for the human complement protein factor B, a class III major histocompatibility complex gene product.

cDNA clones corresponding to a major histocompatibility class III antigen, the complement protein factor B, have been isolated from a human adult liver cDNA library. The clones, ranging in size from 1.0 to 2.3 kilobases, were identified by direct hybridization with two synthetic oligonucleotide mixtures. Two regions of the factor B amino acid sequence, each with minimal ambiguity in codon assignment, were chosen for synthesis of the oligonucleotides. The sequences of two clones have been partially determined. They contain coding information for the amino acid sequence of the Bb fragment of factor B and the entire 3' -untranslated region.

Adult↗
PubMed1982

Biosynthesis of a structurally abnormal C2 complement protein by macrophages from C2-deficient guinea pigs.

In order to characterize a genetic deficiency of C2 in guinea pigs, production of C2 by peritoneal macrophage cultures derived from four normal, four heterozygous deficient, and four homozygous deficient animals was measured functionally and immunochemically after metabolic labeling with 35S-methionine. Macrophage monolayers from homozygous deficient animals failed to secrete hemolytically detectable C2 up to 74 hr in culture. A single cell hemolytic plaque assay also failed to demonstrate any functional C2 production by cells from homozygous deficient animals. No C2 protein was detected in media from three of the four homozygous deficient animals, but in one, apparent C2 fragments were present. In contrast, intracellular C2 protein was identified in all four homozygous deficient cell cultures. Its mobility on SDS-PAGE was slightly faster than normal. Much less abnormal intracellular C2 protein was recovered from homozygous deficient macrophage monolayers than intracellular C2 protein from normal macrophage monolayers. Monolayers from heterozygous animals produced functional and immunochemical C2 at approximately 30% of the normal rate. Normal rates of biosynthesis and secretion of two other MHC-linked class III antigens, C4 and factor B, were detected in macrophage cultures from homozygous and heterozygous deficient animals. These data suggest that a specific defect, i.e. a structural abnormality in C2 protein, underlies C2 deficiency in guinea pigs.

Animals↗
PubMed1981

NH2-terminal structure and cleavage of guinea pig pro-C3, the precursor of the third complement component.

The NH2-terminal structures of the intracellular precursor of the third component of guinea pig complement (pro-C3), synthesized in macrophage cultures, and beta chain of C3 from guinea pig plasma were determined. Six of the first 16 residues of pro-C3 were identified by a microradiosequencing method. All six are nonpolar and are identical with the residues in beta chain of native plasma C3. This establishes beta chain as the NH2-terminal subunit in pro-C3. A comparison of primary structures of guinea pig and human C3 beta chains revealed identity of at least 8 residues within the NH2-terminal decapeptide. Incubation of plasmin with radiolabeled pro-C3 in macrophage lysate resulted in loss of pro-C3 and the generation of a two-chain molecule electrophoretically indistinguishable from native C3. These data indicate similarities between pro-C3 and the precursor of the fourth complement component, pro-C4, with respect to subunit organization, presence of phylogenetically conserved NH2-terminal regions, and the probable mechanism for generation of their respective native proteins.

Amino Acid Sequence↗
PubMed1980

NH2-terminal sequence analysis of pro-C4, the precursor of the fourth component of guinea pig complement.

The amino acid sequence of the NH2-terminal regions of the intracellular precursor of the fourth component of guinea pig complement (pro-C4) and isolated alpha, beta, and gamma chains of native C4, synthesized by peritoneal macrophages in culture, were determined with a microradiosequencing technique. Radiolabeled pro-C4 was immunoprecipitated from cell lysates and native C4 from culture media which contained one of six 3H-amino-acids or [35S]methionine. The purity of these proteins was established and molecular weights were estimated by electrophoresis in sodium dodecyl sulfate. Seventeen of the first 22 residues of pro-C4 were identified. Fifteen of these 17 were nonpolar. The eight amino acids ascertained within the first 9 NH2-terminal residues of guinea pig pro-C4 were identical with those reported for human C4 beta chain, and identity with residues determined for guinea pig C4 beta chain was established. These data indicate that beta chain is the NH2-terminal segment of pro-C4, that no residues are cleaved from the NH2 terminus during the conversion to native C4, and that this segment of the pro-C4 molecule is conserved phylogenetically.

Amino Acid Sequence↗