Surface accessibility and conformational changes in the N-terminal domain of type I inositol trisphosphate receptors: studies using cysteine substitution mutagenesis.

ABSTRACT: To identify surface-accessible residues and monitor conformational changes of the type I inositol 1,4,5-trisphosphate receptor protein in membranes, we have introduced 10 cysteine substitutions into the N-terminal ligand-binding domain. The reactivity of these mutants with progressively larger maleimide-polyethylene glycol derivatives (MPEG) was measured using a gel shift assay of tryptic fragments. The results indicate that the mutations fall into four categories as follows: sites that are highly accessible based on reactivity with the largest 20-kDa MPEG (S2C); sites that are moderately accessible based on reactivity only with 5-kDa MPEG (S6C, S7C, A189C, and S277C); sites whose accessibility is markedly enhanced by Ca(2+) (S171C, S277C, and A575C); and sites that are inaccessible irresp

SUBMITTER: Anyatonwu G 

PROVIDER: S-EPMC2658103 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature