Notes: Transformation of NIH 3T3 Fibroblasts by an Activated Form of p59^hck

Abstract

Phosphorylation of a tyrosine residue near the carboxy terminus of src-family protein tyrosine kinases is believed to regulate the biological activity of these gene products. Conversion of this tyrosine in p59^hck (Tyr-501) to a phenylalanine residue by using oligonucleotide-directed mutagenesis yielded a product (p59^hckF501) with very potent transforming activity. Quantitative analysis by a soft-agar cloning assay revealed that p59^hckF501 was more than 100-fold more effective than a closely related transforming element, p56^lckF505, in colony formation. Cells bearing p59^hckF501 had increased levels of protein phosphotyrosine. The ability of p59^hckF501 to transform NIH 3T3 cells was abolished by a second mutation believed to destroy the ATP-binding domain.