Structural and functional characterization of an incompletely processed form of murine C4 and Slp

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

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The properties of a 128,000-dalton polypeptide, corresponding to the uncleaved α- and γ-chains of the fourth component of murine complement (C4), were studied. A fragment of similar size (137,000 daltons) from the structurally related sex-limited protein (Slp) was also found. These polypeptides have methylamine and iodoacetamide binding sites, suggesting that they, like the α-chains of C4 and Slp, possess an internal thiolester. In tryptic peptide map analysis, extensive homology is seen between the 128,000-dalton fragment and native C4 α- and γ-chains. N-terminal sequences for this fragment and C4α are identical, as are those for the 137,000-dalton slp fragment and Slp α. Although the α-γ fragment, like C4α, undergoes denaturation-dependent autolytic cleavage, unlike C4α, it cannot be cleaved by C1̄. This indicates that some of the properties of C4 do not require the native three-chain structure, whereas others do require it. These findings suggest that the α-γ fragments represent an intermediate step in the processing of the C4 and Slp precursor polypeptides.

Original languageEnglish (US)
Pages (from-to)2336-2341
Number of pages6
JournalJournal of Immunology
Volume128
Issue number5
StatePublished - 1982

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Peptides
Proteins
Complement C4
Iodoacetamide
Protein Precursors
Binding Sites
methylamine

ASJC Scopus subject areas

  • Immunology

Cite this

Structural and functional characterization of an incompletely processed form of murine C4 and Slp. / Karp, D. R.; Capra, J. D.; Atkinson, J. P.; Shreffler, D. C.

In: Journal of Immunology, Vol. 128, No. 5, 1982, p. 2336-2341.

Research output: Contribution to journalArticle

Karp, DR, Capra, JD, Atkinson, JP & Shreffler, DC 1982, 'Structural and functional characterization of an incompletely processed form of murine C4 and Slp', Journal of Immunology, vol. 128, no. 5, pp. 2336-2341.
Karp, D. R. ; Capra, J. D. ; Atkinson, J. P. ; Shreffler, D. C. / Structural and functional characterization of an incompletely processed form of murine C4 and Slp. In: Journal of Immunology. 1982 ; Vol. 128, No. 5. pp. 2336-2341.
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