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Protein kinase C from rainbow trout brain: Identification and characterization of three isozymes
Author(s) -
Brooks S. P. J.,
Storey K. B.
Publication year - 1998
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549800201282
Subject(s) - rainbow trout , isozyme , identification (biology) , biochemistry , chemistry , biology , zoology , computational biology , fishery , fish <actinopterygii> , enzyme , ecology
Free and membrane‐associated fractions of protein kinase C (PKC) from rainbow trout (Onchorynchus mykiss) brain tissue were separated by hydroxylapatite chromatography and characterized kinetically. In both resting fish and in fish swum to exhaustion, approximately 40% of the total PKC activity was bound to membranes. Quantification of the three distinct hydroxylapatite chromatography peaks (PKC types γ, β and α) in cytosolic and membrane fractions revealed different isozyme distributions. The cytosolic fraction contained 21% PKC type γ, 52% PKC type β and 27% PKC type α. The membrane‐associated fraction contained 23% PKC type γ, 28% PKC type β and 49% PKC type α. Kinetic characterization of the three isozymes showed that PKC type γ was almost completely activated by Ca2+ alone whereas PKC type β and PKC type α were 40% and 60% activated by Ca2+. Full activity for all enzymes was observed only in the presence of phosphatidylserine and diacylglycerol. Differences in the kinetic constants for the three isozymes were also apparent. PKC type γ, had a much lower affinity for Histone III‐S when compared with PKC types β and α (100 μg/ml as compared with 1.7 and 5.7 μg/ml). PKC type γ, also had a lower affinity for calcium (0.22 μM) when compared with PKC type β (0.08 μM) and PKC type α (0.05 μM). PKC type α had a lower affinity for phosphatidylserine (8.6 μg/ml) when compared with PKC type γ (0.37 μg/ml) and PKC type β (0.89 μg/ml).