Regulation of type-1 protein phosphatase in a model of metabolic arrest.
Type-1 phosphatase (PP-1) was assessed in foot muscle (FM) and hepatopancreas (HP) of estivating (EST) Otala lactea. Snail PP-1 displayed several conserved traits, including sensitivity to inhibitors, substrate affinity, and reduction in size to a 39 kDa catalytic subunit (PP-1c). During EST, PP-1 activity in FM and HP crude extracts was reduced, though kinetics and protein levels of purified PP-1c isoforms were not altered. PP-1c protein levels increased and decreased in nuclear and glycogen-associated fractions, respectively, during EST. Gel filtration determined that a 257 kDa low K(m) PP-1alpha complex decreased during estivation whereas a 76 kDa high K(m) complex increased in EST. Western blotting confirmed that the 76 kDa protein consisted of PP-1alpha and nuclear inhibitor of PP-1 (NIPP-1). A suppression of PP-1 activity factors in the overall metabolic rate depression in estivating snails and the mechanism is mediated through altered cellular localization and interaction with binding partners.
Ramnanan
Christopher J
CJ
Vanderbilt University School of Medicine, Department of Molecular Physiology, 710 Robinson Research Building, 2200 Pierce Avenue, Nashville, TN 37232, USA. chris.ramnanan@vanderbilt.edu
Storey
Kenneth B
KB
D000818:Animals; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000201:enzymology; D054645:Protein Phosphatase 1 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012758:Shellfish; D012908:Snails / Q000201:enzymology* / Q000378:metabolism
D054645:Protein Phosphatase 1