the two murine gene products exhibit 68% amino acid identity to one another, with most of the sequence variation being located to the linker regions between the sh3 and sh2 domains, and are 96% identical to their human counterparts. while human nck-1 gene has been localised to the 3q21 locus of chromosome 3, the nck-2 gene can be found on chromosome 2 at the 2q12 locus.