caa a22 4500 465826547 CHVBK 20180323112151.0 cr unu---uuuuu 170327e19900801xx s 000 0 eng 10.1007/BF00302597 doi (NATIONALLICENCE)springer-10.1007/BF00302597 cGMP-stimulated protein kinase phosphorylates pyruvate kinase in an anoxia-tolerant marine mollusc [Elektronische Daten] [Stephen Brooks, Kenneth Storey] Summary: A cystosolic protein kinase that phosphorylates pyruvate kinase (PK) in vitro has been identified in crude homogenates of heart, radular retractor, and foot muscle from the anoxia-tolerant marine whelk Busycon canaliculatum. Protein kinase action was measured by following changes in PK kinetic parameters: phosphorylated PK has a higher K m value for phosphoenolpyruvate and a lower I50 value for l-alanine. The crude protein kinase readily phosphorylated PK in a Mg2+-and ATP-dependent manner in the absence of any added effector. This activity was not affected by the addition of either cAMP (a stimulator of protein kinase A) or Ca2+ plus phorbol 12-myristate 13-acetate (stimulators of protein kinase C) to the incubation medium. Addition of cGMP to the homogenate, however, increased the rate of PK phosphorylation giving a 3-4-fold increase in the rate of change in PK kinetic parameters that was readily apparent after 5h. Complete time-courses of changes in PK kinetic parameters in the presence and absence of cGMP showed that cGMP increased the rate, but not the final extent, of PK phosphorylation. These results indicate that PK inactivation by enzyme phosphorylation in response to anoxia in whelk tissues may be mediated by a cyclic GMP stimulated protein kinase in response to changing levels of cGMP. This conclusion was further supported by data indicating that the total activity of protein kinase was the same in both anoxic and aerobic animals, and that the total PK phosphatase activity was also constant. Changes in PK phosphorylation during anoxia are not, therefore, the result of changes in the total amount of protein kinase or phosphatase. Springer-Verlag, 1990 Anaerobiosis nationallicence Pyruvate kinase nationallicence cGMP-dependent protein kinase nationallicence Marine molluscs nationallicence Reversible phosphorylation control of enzymes nationallicence cAMP : adenosine 3′:5′-monophosphate nationallicence cGMP : guanosine 3′:5′-monophosphate nationallicence PK : pyruvate kinase nationallicence PMA : phorbol 12-myristate, 13-acetate nationallicence PEP : phosphoenolpyruvate nationallicence K m : Michaelis constant nationallicence I 50 : inhibitor concentration that reduces enzyme activity by 50% nationallicence Brooks Stephen Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut Storey Kenneth Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut Journal of Comparative Physiology B Springer-Verlag 160/3(1990-08-01), 309-316 0174-1578 160:3<309 1990 160 360 https://doi.org/10.1007/BF00302597 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00302597 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Brooks Stephen Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut NATIONALLICENCE 700 1- Storey Kenneth Institute of Biochemistry, Carleton University, K1S 5B6, Ottawa, Ontario, Canada aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 160/3(1990-08-01), 309-316 0174-1578 160:3<309 1990 160 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer