IMMUNODETECTION OF RAT WALKER-256 TUMOR MITOCHONDRIAL CARNITINE PALMITOYLTRANSFERASE-I AND PALMITOYLTRANSFERASE-II - EVIDENCE FOR THE CONTROL OF CPT-II EXPRESSION BY INSULIN

The purpose of the study was to separate the mitochondrial proteins of rat Walker 256 tumour tissue and perform immunodetection studies to i dentify the carnitine palmitoyltransferase (CPT I) and CPT II proteins previously reported to be present in this tumour (1). CPT protein was undetectable using antibody raised against rat liver CPT I and was th erefore considered to be immunologically different from that found in normal rat tissues such as heart, liver and skeletal muscle. In contra st, CPT II protein was readily detected in Walker 256 tumour and had a n apparent Mr of similar to 70,000, as was found for rat liver. The in vivo treatment of tumour-bearing rats with insulin caused an increase in the expression of CPT II protein in the tumour tissue. The data co nfirm that CPT II can be regulated by insulin and also demonstrate tha t tumour CPT I may be a different isoform from that present in rat liv er.