Identification of Proteins Phosphorylated by Protein Kinase C in Soybean

대두 유식물에서 Protein Kinase C에 의해서 인산화되는 단백질의 동정

The previous report (Chung and Lee, 1992) in our laboratory demonstrated that the protein kinase C (PKC) activator, TPA, promotes the elongation of corn coleoptiles significantly. To understand the role of TPA on the growth, substrates of PKC were investigated using PKC partially purified from soybean by DEAE-52 cellulose column. The enzyme activity increased about 5-fold in the presence of $Ca^{2+}$, phosphatidylserine and diolein compared with that in the absence of these reagents. Phosphorylation of both cytosol and membrane proteins by the purified PKC increased in the presence of $Ca^{2+}$ compared with that of EGTA treatment. However, the phosphorylation did not increase markedly by treatment with TPA or phosphatidylserine and diolein in the presence of $Ca^{2+}$ compared with $Ca^{2+}$ alone. The decrease, in phosphorylation of 100, 61 and 43 Kd proteins of the cytosol, and 140, no, 66, 47 and 32 Kd membrane proteins in hypocotyls, and 140, no, 66, 47, 33, 31 and 16 Kd membrane proteins in the root was observed in the presence of PKC inhibitor staurosporine (5T A). These results suggest that subatrates of PKC in soybean may be 110, 63 and 41 Kd proteins of the cytosol, and 140, 110, 66, 47 and 32 Kd membrane proteins in the subapical region of the hypocotyl, and 140, 110, 66, 47, 33, 31 and 16 Kd membrane proteins of the root.e root.

DEAE-52 cellulose column을 이용하여 부분적으로 분리한 PKC를 이용하여 대두 유 식물 하배축 정단부와 뿌리에서 각각 분리한 세포질 단백질과 막 단백질의 인산화 실험을 통해 PKC의 기질이 되는 단백질을 조사하여 보았다. PKC의 기질은 세포질 단백질의 경우 100, 63 그리고 41 Kd 단백질들이며, 막 단백질 중 하배축 정단부의 경우는 140, 110, 66, 47 그리고 32 Kd 단백질들이며, 뿌리의 경우는 140, 110, 66, 47, 33, 31, 16 Kd 단백질들이라고 생각된다.