Molecular cloning, genomic organization, and expression of three chicken 5'-AMP-activated protein kinase gamma subunit genes.

The 5'-AMP-activated protein kinase (AMPK) plays a key role in regulating cellular energy homeostasis. The AMPK is a heterotrimeric enzyme complex that consists of 1 catalytic (alpha) and 2 regulatory (beta and gamma) subunits. Mutations of the gamma subunit genes are known to affect AMPK functioning. In this study, we characterized the genomic organization and expression of 3 chicken AMPK gamma subunit genes (cPRKAG). Alternative splicing of the second exon of the cPRKAG1 gene resulted in 2 transcript variants that code for predicted proteins of 298 and 276 amino acids. Use of an alternate promoter and alternative splicing of the cPRKAG2 gene resulted in 4 transcript variants that code for predicted proteins of 567, 452, 328, and 158 amino acids. Alternative splicing of exon 3 of the cPRKAG3 gene resulted in the production of "long" and "short" transcript variants that code for predicted proteins of 382 and 378 amino acids, respectively. We found evidence for differential expression of individual gamma subunit gene transcript variants and, in some cases, tissue-specific expression was observed. The cPRKAG subunit genes displayed similar structural features and high sequence homology compared with corresponding mammalian gamma subunit gene homologues.