Casein kinase II stimulates rat liver mitochondrial glycerophosphate acyltransferase activity.
Rat liver mitochondrial glycerophosphate acyltransferase (mtGAT) possesses 14 consensus sites for casein kinase II (CKII) phosphorylation. To study the functional relevance of phosphorylation to the activity of mtGAT, we treated isolated rat liver mitochondria with CKII and found that CKII stimulated mtGAT activity approximately 2-fold. Protein phosphatase-lambda treatment reversed the stimulation of mtGAT by CKII. Labeling of both solubilized and non-solubilized mitochondria with CKII and [gamma-32P]ATP resulted in a 32P-labeled protein of 85kDa, the molecular weight of mtGAT. Our findings suggest that CKII stimulates mtGAT activity by phosphorylation of the acyltransferase. The significance of this observation with respect to hormonal control of the enzyme is discussed.
Department of Biological Sciences, St. John's University, 8000 Utopia Pkwy, 11439, Jamaica, NY, USA.
Thomas M
TM
Onorato
Dipak
D
Haldar
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D047390:Casein Kinase II; D004789:Enzyme Activation; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020539:Sequence Analysis, Protein
D024101:Mitochondrial Proteins; D000255:Adenosine Triphosphate; D005992:Glycerol-3-Phosphate O-Acyltransferase; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D010749:Phosphoprotein Phosphatases