BOVINE HEART FRUCTOSE 6-P,2-KINASE - FRUCTOSE 2,6-BISPHOSPHATASE MESSENGER-RNA AND GENE STRUCTURE

Previously we described the coding region of bovine heart Fructose 6-P ,2-kinase:Fructose 2,6-bisphosphatase as determined from cDNA. We have isolated several overlapping clones and determined the DNAs which enc ode the entire mRNA of bovine heart bifunctional enzyme, including the 5'- and 3'-noncoding regions. The exon-intron structure of the 27-kb gene was determined and shown to consist of 16 exons. There are one pr imary and two secondary transcription initiation sites with the coding region beginning at exon 2. Exons 3-7 encode the Fructose 6-P,2-kinas e domain, and exons 9-14 encode the Fructose 2,6-biphosphatase domain. Exon 15 is a unique exon for the heart type isozyme and contains the phosphorylation sites for protein kinases A and C. Alternative splicin g of this exon accounts for the expression of two heart type isozymes in cardiac muscle. Exon 16 (also unique), 1820 bp long and located 7 k b downstream of exon 15, encodes the short C-terminus of the enzyme an d is completely different from that of the rat heart bifunctional enzy me gene. (C) 1994 Academic Press, Inc.