SP-40,40, a Newly Identified Normal Human Serum Protein Found in the SC5b-9 Complex of Complement and in the Immune Deposits in Glomerulonephritis

Overview

Journal J Clin Invest

Specialty General Medicine

Date 1988 Jun 1

PMID 2454950

Citations 72

Authors

B F Murphy

L Kirszbaum

I D Walker

A J dApice

Affiliations

Soon will be listed here.

Abstract

We report herein the isolation and initial characterization of a novel protein, termed SP-40,40, which is present at moderate levels (35-105 micrograms/ml) in normal human serum. SP-40,40 is deposited in the renal glomeruli of patients with glomerulonephritis but is not found in normal glomeruli. The protein is a heterodimeric structure of relative molecular mass 80 kD, both chains of which are of a similar size (40 kD). The amino-terminal sequences of both chains are unrelated to one another and possess no significant homology to any known protein sequence. The tissue distribution of SP-40,40 closely resembles that of the terminal complement components and its physicochemical properties are similar to, but distinct from, those of the S protein of complement. We have identified SP-40,40 in the SC5b-9 complex of complement and have demonstrated incorporation of labeled SP-40,40 into this complex. These data suggest that SP-40,40 is an additional component of SC5b-9.

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