An ACTH-activated protein tyrosine phosphatase (PTP) is modulated by PKA-mediated phosphorylation.
In adrenal cortex, ACTH regulation of steroidogenesis depends on PKA-dependent serine/threonine phosphorylation and also on the activity of protein tyrosine phosphatases (PTPs). In addition, ACTH increases total PTPs involving at least three soluble PTPs (50, 82 and 115 kDa). Serine/threonine phosphorylation of these enzymes themselves could be a regulatory mechanism of their activity since the increase of total PTP activity is dependent on PKA-activation. In this report we analyzed the effect of in vitro phospho-dephosphorylation processes on the activity displayed by the ACTH-activated PTP of 115 kDa. Using an in-gel PTP assay we demonstrate that dephosphorylation catalyzed by potato acid phosphatase (PAP) reduces the activity of the 115 kDa PTP present in ZF from ACTH-treated animals and PKA-mediated phosphorylation reverses this effect.
Paz
C
C
Dept. of Biochemistry, School of Medicine, University of Buenos Aires, Argentina. crispaz@fmed.uba.ar
Cornejo Maciel
F
F
Poderoso
C
C
Gorostizaga
A
A
Podestá
E J
EJ
D000135:Acid Phosphatase / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D008297:Male; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015383:Zona Fasciculata / Q000201:enzymology
D000324:Adrenocorticotropic Hormone; D017868:Cyclic AMP-Dependent Protein Kinases; D000135:Acid Phosphatase; D017027:Protein Tyrosine Phosphatases