Identification and functional analysis of truncated human glutamic acid decarboxylase 65.
Human brain glutamate decarboxylase 65 (hGAD65) was found to exist as full-length and truncated forms when the glutathione S-transferase-tagged hGAD65 fusion protein was subjected to factor Xa cleavage. The truncated form is produced by cleavage at arginine 69 based on N-terminal amino acid sequence analysis, and has a molecular weight of 58 kD. It is resistant to further factor Xa cleavage or mild trypsin treatment and is more active and more stable than the full-length form. Both the full-length and truncated forms of GAD are also observed in brain preparations in the presence of protease inhibitors. Furthermore, full-length GAD could be converted to the truncated form by endogenous proteases, suggesting that the conversion of full-length to truncated GAD mediated by endogenous protease may represent an important mechanism in the regulation of GABA biosynthesis in the brain.
Department of Biomedical Science, Florida Atlantic University, Boca Raton, FL 33431, USA.
Jianning
J
Wei
Ying
Y
Jin
Heng
H
Wu
Di
D
Sha
Jang-Yen
JY
Wu
D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D015951:Factor Xa / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008970:Molecular Weight; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D015951:Factor Xa; D005968:Glutamate Decarboxylase