1apq | pdb_00001apq
STRUCTURE OF THE EGF-LIKE MODULE OF HUMAN C1R, NMR, 19 STRUCTURES
Structural highlights
Function[C1R_HUMAN] C1r B chain is a serine protease that combines with C1q and C1s to form C1, the first component of the classical pathway of the complement system. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe calcium-dependent interaction between C1r and C1s, the two homologous serine proteases of the first component of human complement C1, is mediated by their N-terminal regions. The latter comprise an epidermal growth factor (EGF)-like module exhibiting the consensus sequence characteristic of Ca(2+)-binding EGF modules, surrounded by two CUB modules. Due to its Ca2+ binding ability, the C1r EGF-like module (C1r-EGF) is supposed to participate in the C1r-C1s interaction. An additional interesting feature of C1r-EGF is the unusually large loop connecting the first two conserved cysteine residues. The solution structure of synthetic C1r-EGF (residues 123-175) has been determined using nuclear magnetic resonance and combined simulated annealing-restrained molecular dynamics calculations. The resulting family of 19 structures is characterized by a well-ordered C-terminal part (residues Cys 144-Ala174) with a backbone rmsd of 0.7 A and a disordered N-terminal, including the large loop between the first two cysteines (Cys129 and Cys144). This loop is known to be surface exposed and may be expected to participate in domain-domain or protein-protein interactions. In its C-terminal part, C1r-EGF possesses the characteristic EGF fold with a major and a minor beta-sheet. The latter comprises a beta-bulge, and comparison with other EGF-like modules reveals the existence of two distinct structural and sequential motifs in the bulged part. Additional experiments in the presence of 80 mM Ca2+ did not show significant structural variation of C1r-EGF, in keeping with previous observations on blood-clotting factors IX and X. Solution structure of the epidermal growth factor (EGF)-like module of human complement protease C1r, an atypical member of the EGF family.,Bersch B, Hernandez JF, Marion D, Arlaud GJ Biochemistry. 1998 Feb 3;37(5):1204-14. PMID:9477945[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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