Catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate, to initiate a change in cell activity [goid 4714] [evidence IEA]; Interacting selectively with ATP, adenosine 5'-triphosphate, a universally important coenzyme and enzyme regulator [goid 5524] [evidence IEA]; Interacting selectively with a nucleotide, any compound consisting of a nucleoside that is esterified with (ortho)phosphate or an oligophosphate at any hydroxyl group on the ribose or deoxyribose moiety [goid 166] [evidence IEA]; Catalysis of the reaction: ATP + a protein-L-tyrosine = ADP + a protein-L-tyrosine phosphate, to initiate a change in cell activity [goid 4714] [evidence IEA]; Combining with an extracellular or intracellular messenger to initiate a change in cell activity, and spanning to the membrane of either the cell or an organelle [goid 4888] [pmid 7514177] [evidence ISS]; Interacting selectively with ATP, adenosine 5'-triphosphate, a universally important coenzyme and enzyme regulator [goid 5524] [evidence IEA]; Catalysis of the transfer of a group, e.g. a methyl group, glycosyl group, acyl group, phosphorus-containing, or other groups, from one compound (generally regarded as the donor) to another compound (generally regarded as the acceptor). Transferase is the systematic name for any enzyme of EC class 2 [goid 16740] [evidence IEA]; Interacting selectively with any growth factor, proteins or polypeptides that stimulate a cell or organism to grow or proliferate [goid 19838] [pmid 11389077] [evidence IPI]; Interacting selectively with any growth factor, proteins or polypeptides that stimulate a cell or organism to grow or proliferate [goid 19838] [pmid 7514177] [evidence ISS]; Increases the activity of a protein tyrosine kinase, an enzyme which phosphorylates a tyrosyl phenolic group on a protein [goid 30296] [pmid 7556068] [evidence IDA]; Interacting selectively with an identical protein to form a homodimer [goid 42803] [pmid 11389077] [evidence NAS]; Interacting selectively with a nonidentical protein to form a heterodimer [goid 46982] [pmid 10572067] [evidence IDA]