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Expression of ras oncogene leads to down-regulation of protein kinase C

✍ Scribed by Tina Haliotis; William Trimble; Sue Chow; Shelley Bull; Gordon Mills; Peggy Girard; J. F. Kuo; Nobumichi Hozumi

Book ID
102865347
Publisher
John Wiley and Sons
Year
1990
Tongue
French
Weight
869 KB
Volume
45
Category
Article
ISSN
0020-7136

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✦ Synopsis

The effect of mutated c-Ha-ras expression on Caz+ and phospholipid-dependent protein kinase C (PKC) activity during the process of transformation was analysed using an inducible metallothionein-ras hybrid oncogene system. A close correlation was found between the timing of ras expression and the loss of PKC enzymatic activity measured in a cell-free system. Examination of the subcellular distribution of the enzyme in inducible and constitutive ras-transformants revealed that expression of ras was associated with an apparent translocation of PKC to the plasma membrane concomitant with down-regulation of PKC enzymatic activity in particulate as well as cytosolic fractions. Quantitation of PKC protein utilizing a PKC-specific antiserum showed that ras expression was associated with a decrease in the total amount of PKC protein present in the cell. We conclude that transformation by c-Ha-ras is accompanied by down-regulation of PKC activity and that the basis of this effect may, to a large extent, lie in the down-regulation of the amount of PKC protein.

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