GRB2 Related Adaptor Protein 2 (GRAP2)

The predicted 330-amino acid GRAP2 protein contains an SH2 domain flanked by 2 SH3 domains. These domains are arranged in the same configuration as, and share a high degree of amino acid identity with, the SH2 and SH3 domains of the GRB2 and GRAP proteins. However, GRAP2 contains an additional 120-amino acid glutamine-rich domain between its SH2 domain and C-terminal SH3 domain.

The interaction of GRAP2 with GAB1 appears to be mediated through its C-terminal SH3 domain. Northern blot analysis detected major 1.4- and 4.0-kb GRAP2 transcripts in thymus, spleen, peripheral blood leukocytes, and chronic myelogenous and lymphoblastic leukemia cell lines, with the highest expression in thymus.