Hematopoietic SH2 Domain Containing Protein (HSH2D)

The deduced 352-amino acid protein contains an N-terminal proline-rich domain, followed by an SH2 domain and 3 additional proline-rich domains in the C-terminal half. The proline-rich regions contain the PxxP motif characteristic of SH3 domain-binding sites. Northern blot analysis detected a 2.2-kb transcript predominantly expressed in peripheral blood leukocytes. RT-PCR detected abundant expression in leukocytes and spleen, with weaker expression in prostate, thymus, heart, small intestine, and placenta. Expression was detected in resting and activated T and B cells, in monocytes, and in several leukemia cell lines. Little to no expression was detected in an embryonic kidney cell line and in a neuronally-differentiated teratocarcinoma cell line. Subcellular localization of fluorescence-tagged HSH2 showed distribution to both the nucleus and cytoplasm.