The deduced 214-amino acid protein has a central EF-hand Ca(2+)-binding domain, several phosphorylation sites, and an N-myristoylation site. Tesc expression in mouse testis beginning at 11.5 days postcoitum, with peak expression at 14.5 days postcoitum. Weaker expression was detected in adult testis and ovary, and Tesc was also expressed in testis devoid of germ cells. The deduced 214-amino acid protein, which shares 96.7% identity with mouse Tsc, contains a central EF-hand Ca(2+)-binding domain and an N-myristoylation site. Northern blot analysis detected a 1.3-kb transcript highly expressed in heart and weakly expressed in adult testis and salivary gland. PCR analysis detected TSC expression in placenta. Overexpressed epitope-labeled TSC localized to the cytosol and lamellipodia of mouse fibroblasts.