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.
Wei
Jianning
J
Department of Biomedical Science, Florida Atlantic University, Boca Raton, FL 33431, USA.
Jin
Ying
Y
Wu
Heng
H
Sha
Di
D
Wu
Jang-Yen
JY
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