| Co-Investigator(Kenkyū-buntansha) |
TACHIBANA Hideki Kobe University, Faculty of Science, Associate Professor, 理学部, 助教授 (70126118)
OGITA Kouji Kobe University School of Medicine, Assistant Professor, 医学部, 助手 (60204103)
KIKKAWA Ushio Kobe University School of Medicine, Lecturer, 医学部, 講師 (40150354)
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| Research Abstract |
The mammarian protein Idnase C (PKC) exists as a large family of multiple subspecies. At present, 8 subspecies of PKC (alpha, betaI, betaII, gamma, delta, epsilon, zeta, and eta (L) ) have been identified. To find out subspecies-specific activators or inhibitors, it is essential to purify each subspecies. Up to now, alpha, beta (betaI +betaII) and gamma subspecies of PKC have been purified from rat brain and their enzymological properties have been clarified. However, other subspecies have not been studied well. In this study, delta, epsilon, and zeta subspecies of PKC were isolated from rat brain and characterized in comparison with those obtained from COS-7 expression systems. Subspecies-pacific anti-peptide antisera were prepared and used to identify each PKC subspecies. The isolated enzymes were different from each other in the mode of activation by various substances and in substrate specificity.
In order to clarify the roles of PKC subspecies in the cell cycle control, we also isolated PKC subspecies from S. cerevisiae and-from Xenopus oocytes. The yeast enzyme was isolated as a single entity and found to be quite different from mammalian enzymes in that it was not activated by the tumor-promoting phorbol esters, although it was activated by diacylglycerol in the presence of phosphatidylserine. On the other hand, the Xenopus PKC was isolated as two subtly different enzymes. Both of them were very similar to the mammalian alpha-PKC in their enzymological properties such as dependency on calcium and activation by phorbol esters. However, they responded differently in oocytes treated widi the tumor promoter. Namely, one PKC disappeared very rapidly upon phorbol ester treatment, while the other remained unchanged up to 4 hr.
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