Phosphorylation of rat liver mitochondrial carnitine palmitoyltransferase-I: effect on the kinetic properties of the enzyme |
| |
Authors: | Kerner Janos Distler Anne M Minkler Paul Parland William Peterman Scott M Hoppel Charles L |
| |
Institution: | Department of Nutrition, Biochemistry, and Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, USA. |
| |
Abstract: | Hepatic carnitine palmitoyltransferase-I (CPT-IL) isolated from mitochondrial outer membranes obtained in the presence of protein phosphatase inhibitors is readily recognized by phosphoamino acid antibodies. Mass spectrometric analysis of CPT-IL tryptic digests revealed the presence of three phosphopeptides including one with a protein kinase CKII (CKII) consensus site. Incubation of dephosphorylated outer membranes with protein kinases and gamma-32P]ATP resulted in radiolabeling of CPT-I only by CKII. Using mass spectrometry, only one region of phosphorylation was detected in CPT-I isolated from CKII-treated mitochondria. The sequence of the peptide and position of phosphorylated amino acids have been determined unequivocally as FpSSPETDpSHRFGK (residues 740-752). Furthermore, incubation of dephosphorylated outer membranes with CKII and unlabeled ATP led to increased catalytic activity and rendered malonyl-CoA inhibition of CPT-I from competitive to uncompetitive. These observations identify a new mechanism for regulation of hepatic CPT-I by phosphorylation. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|