2okk

From Proteopedia

The X-ray crystal structure of the 65kDa isoform of Glutamic Acid Decarboxylase (GAD65)

Overview

Gamma-aminobutyric acid (GABA) is synthesized by two isoforms of the, pyridoxal 5'-phosphate-dependent enzyme glutamic acid decarboxylase (GAD65, and GAD67). GAD67 is constitutively active and is responsible for basal, GABA production. In contrast, GAD65, an autoantigen in type I diabetes, is, transiently activated in response to the demand for extra GABA in, neurotransmission, and cycles between an active holo form and an inactive, apo form. We have determined the crystal structures of N-terminal, truncations of both GAD isoforms. The structure of GAD67 shows a tethered, loop covering the active site, providing a catalytic environment that, sustains GABA production. In contrast, the same catalytic loop is, inherently mobile in GAD65. Kinetic studies suggest that mobility in the, catalytic loop promotes a side reaction that results in cofactor release, and GAD65 autoinactivation. These data reveal the molecular basis for, regulation of GABA homeostasis.

About this Structure

2OKK is a Single protein structure of sequence from Homo sapiens with and as ligands. Active as Glutamate decarboxylase, with EC number 4.1.1.15 Full crystallographic information is available from OCA.

Reference

GABA production by glutamic acid decarboxylase is regulated by a dynamic catalytic loop., Fenalti G, Law RH, Buckle AM, Langendorf C, Tuck K, Rosado CJ, Faux NG, Mahmood K, Hampe CS, Banga JP, Wilce M, Schmidberger J, Rossjohn J, El-Kabbani O, Pike RN, Smith AI, Mackay IR, Rowley MJ, Whisstock JC, Nat Struct Mol Biol. 2007 Apr;14(4):280-6. Epub 2007 Mar 25. PMID:17384644

Page seeded by OCA on Wed Jan 23 15:32:27 2008