Increased adenosine deaminase synthesis and messenger RNA activity in deoxycoformycin-resistant cells.

S W Hunt,P A Hoffee

doi:10.1016/s0021-9258(18)33216-2

Abstract

The basis for the increased adenosine deaminase activity in deoxycoformycin-resistant rat hepatoma cells was investigated. Three variant cell lines with different levels of adenosine deaminase activity showed increases in the relative rate of synthesis of the enzyme in vivo. No difference in the rate of degradation of the enzyme was seen between the parental cell line and one variant cell line which exhibits a 180-fold increase in adenosine deaminase activity. Polysomal RNA isolated from this variant exhibited a 175-fold increase in the ability to direct the synthesis of adenosine deaminase in vitro.

Highlights

The basis for the increased adenosine deaminase activity in deoxycoformycin-resistantrat hepatoma cells was investigated
We have examined the rates of synthesis and degradation of the enzyme, as well as the adenosine deaminase mRNA activity in dCF-sensitive and -resistant cells
We conclude that the increasedenzyme activity in dCF-resistant cells is due to an increased rateof synthesis which is correlatedwith increased adenosine deaminasemRNA activity

Summary

Introduction

The basis for the increased adenosine deaminase activity in deoxycoformycin-resistantrat hepatoma cells was investigated. We have examined the rates of synthesis and degradation of the enzyme, as well as the adenosine deaminase mRNA activity in dCF-sensitive and -resistant cells. Reactions contained 50-250 pJ of labeled cell extract, 1-2 pg of purified adenosine deaminase and 40 pgof purified IgG.

Results

Conclusion