Characterization of the M(r) difference between secreted murine fourth component of complement and the major plasma form: Evidence for carboxyl-terminal cleavage of the α chain

D. R. Karp, D. C. Shreffler, J. P. Atkinson

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The α-chain of murine fourth component of complement (C4) secreted by cells in vitro and in vivo has a M(r) that is larger by ~4,000 than that of the α-chain of the principal form of C4 in plasma. By using in vivo labeling of C4 with [35S]methionine C4 was shown to be first synthesized with the higher M(r) ('secreted') α-chain, which was then quickly processed (t(1/2)~1 hr) extracellularly to the mature ('plasma') C4 possessing the lower M(r) α-chain. Both forms of C4 were functional as assayed by the ability of their α-chains to be cleaved by the protease C1̄, to bind methylamine, and to undergo denaturation-dependent autolysis. When secreted C4 and plasma C4 were activated to C4b, the M(r) difference of 4,000 was maintained in the α'-chains. The M(r) difference was localized to the carboxyl-terminal autolytic fragment of the α-chain and was unaffected by the removal of carbohydrate. C4 from resident peritoneal macrophage cultures could be converted to the plasma form by incubation with heparin/plasma. This conversion could be blocked by EDTA or 1,10-phenanthroline. These data suggest that an enzyme, presumably a neutral proteinase present in mouse plasma, cleaves the carboxyl terminus of newly synthesized C4 α-chains, thereby creating the major form of C4 in plasma.

Original languageEnglish (US)
Pages (from-to)6666-6670
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume79
Issue number21 I
StatePublished - 1982

Fingerprint

Complement C4
Autolysis
Peritoneal Macrophages
Edetic Acid
Methionine
Heparin
Peptide Hydrolases
Carbohydrates
Enzymes
protease C1
In Vitro Techniques
1,10-phenanthroline
methylamine

ASJC Scopus subject areas

  • General
  • Genetics

Cite this

@article{80471866a99f4ec0b366da1075efd08a,
title = "Characterization of the M(r) difference between secreted murine fourth component of complement and the major plasma form: Evidence for carboxyl-terminal cleavage of the α chain",
abstract = "The α-chain of murine fourth component of complement (C4) secreted by cells in vitro and in vivo has a M(r) that is larger by ~4,000 than that of the α-chain of the principal form of C4 in plasma. By using in vivo labeling of C4 with [35S]methionine C4 was shown to be first synthesized with the higher M(r) ('secreted') α-chain, which was then quickly processed (t(1/2)~1 hr) extracellularly to the mature ('plasma') C4 possessing the lower M(r) α-chain. Both forms of C4 were functional as assayed by the ability of their α-chains to be cleaved by the protease C1̄, to bind methylamine, and to undergo denaturation-dependent autolysis. When secreted C4 and plasma C4 were activated to C4b, the M(r) difference of 4,000 was maintained in the α'-chains. The M(r) difference was localized to the carboxyl-terminal autolytic fragment of the α-chain and was unaffected by the removal of carbohydrate. C4 from resident peritoneal macrophage cultures could be converted to the plasma form by incubation with heparin/plasma. This conversion could be blocked by EDTA or 1,10-phenanthroline. These data suggest that an enzyme, presumably a neutral proteinase present in mouse plasma, cleaves the carboxyl terminus of newly synthesized C4 α-chains, thereby creating the major form of C4 in plasma.",
author = "Karp, {D. R.} and Shreffler, {D. C.} and Atkinson, {J. P.}",
year = "1982",
language = "English (US)",
volume = "79",
pages = "6666--6670",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "21 I",

}

TY - JOUR

T1 - Characterization of the M(r) difference between secreted murine fourth component of complement and the major plasma form

T2 - Evidence for carboxyl-terminal cleavage of the α chain

AU - Karp, D. R.

AU - Shreffler, D. C.

AU - Atkinson, J. P.

PY - 1982

Y1 - 1982

N2 - The α-chain of murine fourth component of complement (C4) secreted by cells in vitro and in vivo has a M(r) that is larger by ~4,000 than that of the α-chain of the principal form of C4 in plasma. By using in vivo labeling of C4 with [35S]methionine C4 was shown to be first synthesized with the higher M(r) ('secreted') α-chain, which was then quickly processed (t(1/2)~1 hr) extracellularly to the mature ('plasma') C4 possessing the lower M(r) α-chain. Both forms of C4 were functional as assayed by the ability of their α-chains to be cleaved by the protease C1̄, to bind methylamine, and to undergo denaturation-dependent autolysis. When secreted C4 and plasma C4 were activated to C4b, the M(r) difference of 4,000 was maintained in the α'-chains. The M(r) difference was localized to the carboxyl-terminal autolytic fragment of the α-chain and was unaffected by the removal of carbohydrate. C4 from resident peritoneal macrophage cultures could be converted to the plasma form by incubation with heparin/plasma. This conversion could be blocked by EDTA or 1,10-phenanthroline. These data suggest that an enzyme, presumably a neutral proteinase present in mouse plasma, cleaves the carboxyl terminus of newly synthesized C4 α-chains, thereby creating the major form of C4 in plasma.

AB - The α-chain of murine fourth component of complement (C4) secreted by cells in vitro and in vivo has a M(r) that is larger by ~4,000 than that of the α-chain of the principal form of C4 in plasma. By using in vivo labeling of C4 with [35S]methionine C4 was shown to be first synthesized with the higher M(r) ('secreted') α-chain, which was then quickly processed (t(1/2)~1 hr) extracellularly to the mature ('plasma') C4 possessing the lower M(r) α-chain. Both forms of C4 were functional as assayed by the ability of their α-chains to be cleaved by the protease C1̄, to bind methylamine, and to undergo denaturation-dependent autolysis. When secreted C4 and plasma C4 were activated to C4b, the M(r) difference of 4,000 was maintained in the α'-chains. The M(r) difference was localized to the carboxyl-terminal autolytic fragment of the α-chain and was unaffected by the removal of carbohydrate. C4 from resident peritoneal macrophage cultures could be converted to the plasma form by incubation with heparin/plasma. This conversion could be blocked by EDTA or 1,10-phenanthroline. These data suggest that an enzyme, presumably a neutral proteinase present in mouse plasma, cleaves the carboxyl terminus of newly synthesized C4 α-chains, thereby creating the major form of C4 in plasma.

UR - http://www.scopus.com/inward/record.url?scp=0020211350&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0020211350&partnerID=8YFLogxK

M3 - Article

C2 - 6959144

AN - SCOPUS:0020211350

VL - 79

SP - 6666

EP - 6670

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 21 I

ER -