1uow

From Proteopedia

Revision as of 15:55, 18 December 2007

CALCIUM BINDING DOMAIN C2B

Overview

Synaptotagmin I has two tandem Ca(2+)-binding C(2) domains, which are, essential for fast synchronous synaptic transmission in the central, nervous system. We have solved four crystal structures of the C(2)B, domain, one of them in the cation-free form at 1.50 A resolution, two in, the Ca(2+)-bound form at 1.04 A (two bound Ca(2+) ions) and 1.65 A (three, bound Ca(2+) ions) resolution and one in the Sr(2+)-bound form at 1.18 A, (one bound Sr(2+) ion) resolution. The side chains of four highly, conserved aspartic acids (D303, D309, D363, and D365) and two main chain, oxygens (M302:O and Y364:O), together with water molecules, are in direct, contact with two bound Ca(2+) ions (sites 1 and 2). At higher Ca(2+), concentrations, the side chain of N333 rotates and cooperates with D309 to, generate a third Ca(2+) coordination site (site 3). Divalent cation, binding sites 1 and 2 in the C(2)B domain were previously identified from, NMR NOE patterns and titration studies, supplemented by site-directed, mutation analysis. One difference between the crystal and NMR studies, involves D371, which is not involved in coordination with any of the, identified Ca(2+) sites in the crystal structures, while it is coordinated, to Ca(2+) in site 2 in the NMR structure. In the presence of Sr(2+), which, is also capable of triggering exocytosis, but with lower efficiency, only, one cation binding site (site 1) was occupied in the crystallographic, structure.

About this Structure

1UOW is a Single protein structure of sequence from Rattus norvegicus with CA, ACT and GOL as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Crystallographic identification of Ca2+ and Sr2+ coordination sites in synaptotagmin I C2B domain., Cheng Y, Sequeira SM, Malinina L, Tereshko V, Sollner TH, Patel DJ, Protein Sci. 2004 Oct;13(10):2665-72. Epub 2004 Aug 31. PMID:15340165

Page seeded by OCA on Tue Dec 18 18:05:30 2007