T-Lymphocyte Specific Adaptor Protein (TSAd)

TSAd encodes an adaptor protein thought to function in T-cell signal transduction. The predicted 389-amino acid SH2D2A protein contains an Src homology-2 (SH2) domain, putative SH3 domain-binding motifs, and putative phosphotyrosine-binding domain (PTB)-binding motifs, but no catalytic domains. The authors also isolated cDNAs representing alternatively spliced SH2D2A transcripts that encode deduced 361- and 399-amino acid proteins. Northern blot analysis detected an approximately 1.7-kb SH2D2A transcript in peripheral blood leukocytes, thymus, and spleen. SH2D2A was expressed in activated T cells, but not in resting T cells or in B cells. Its expression was rapidly induced after activation of T cells. Antiserum raised against SH2D2A reacted with a 52-kD protein on Western blots of T-cell lysates.