ORGANIZATION OF THE HUMAN GLUCOKINASE REGULATOR GENE GCKR

Glucokinase plays an important role in regulating insulin secretion in response to changes in blood glucose levels. As a result, one form of maturity onset diabetes of the young (MODY) results from haploinsuffi ciency of glucokinase. In both liver and pancreatic islet, glucokinase is allosterically regulated by an inhibitory protein (glucokinase reg ulatory protein, GCKR). GCKR has therefore become an important gene fo r functional analysis in type 2 diabetes. To allow genetic assessment of any such role, we have determined the structure of the human GCKR g ene. Characterization of P1 and YAC clones containing GCKR shows it to consist of 19 exons spanning 27 kb. RT-PCR, RACE, and RNase protectio n experiments defined a transcriptional start site for GCKR 66 bp upst ream of the initiation codon, but provided no evidence for islet cell specific alternative splicing in the rat. By SSCP screening, a common polymorphic sequence variant has been defined within exon 15 of human GCKR, at nt 1400 of the cDNA. This alters amino acid residue 446 from proline, conserved in rat and Xenopus, to leucine. (C) 1998 Academic P ress.