PMID: 2096998Dec 1, 1990Paper

Protein tyrosine kinases in human breast cancer: kinetic properties and evidence for the presence of two forms of native enzyme

Breast Cancer Research and Treatment
Y Durocher, S Chevalier

Abstract

The protein tyrosine kinase (PTK) of human breast tumors classified as positive (TM+) or negative (TM-) according to their estrogen and progestin receptor levels was partially characterized with regard to its distribution, kinetic parameters, molecular size, and ability to phosphorylate endogenous mammary proteins. For both types of tumors, PTK activity depended upon the presence of Mn++ (2-5 mM) and/or Mg++ (10-20 mM). The activities, total (per g of tissue) and specific (per mg of protein), were similar for both types of tumors, and an average of 60% of activity was located in cytosolic fractions. The autoradiographic detection of alkali-resistant phosphoproteins after SDS-PAGE showed very similar patterns between corresponding fractions from both types of tumors. Upon gel filtration, two peaks of activity of apparent Mr 245 kDa (peak I) and 47 kDa (peak II) were observed. Peak II was found in both cytosols and extracts from particulate fractions, while peak I was present only in the latter fraction for both TM+ and TM- tumors. The apparent Km's for ATP ranged from 4.1 to 6.6 microM, and from 11 to 34 micrograms/ml for the synthetic substrate poly [Glu80, Tyr20], at an optimal pH of 6.5-7.5. When endogenous alkali-resistant p...Continue Reading

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Citations

Jan 1, 1993·Breast Cancer Research and Treatment·E E LowerO J Martelo
Jan 1, 1993·Breast Cancer Research and Treatment·M BollaE M Chambaz
Sep 1, 1995·Breast Cancer Research and Treatment·E E LowerS Heffelfinger
Jan 1, 1996·Breast Cancer Research and Treatment·M BollaE Chambaz
Aug 21, 2002·Breast Cancer Research and Treatment·Béatrice Rostaing-PuissantMichel Bolla
Aug 13, 2013·Therapeutic Apheresis and Dialysis : Official Peer-reviewed Journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy·Maja Martinuč BergočJernej Pajek

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