1apq
From Proteopedia
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| Sites: | |||||||
| Activity: | Complement subcomponent C1r, with EC number 3.4.21.41 | ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
STRUCTURE OF THE EGF-LIKE MODULE OF HUMAN C1R, NMR, 19 STRUCTURES
Overview
The 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.
About this Structure
1APQ is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Sun Mar 30 18:45:06 2008
