Characterization of the murine thrombospondin gene.

Thrombospondin is an adhesive glycoprotein that supports cell attachment, spreading, and migration. The murine thrombospondin gene is approximately 18 kb in length and includes 22 exons. Interspecific backcross analysis using progeny derived from matings of (C57BL/6J x Mus spretus) F1 x C57BL/6J mice indicates that the thrombospondin gene is tightly linked to the Fshb, Actcl, Ltk, and B2M loci on murine chromosome 2. The sequence of the murine gene is very similar to that of the human gene in (1) regions of the promoter, (2) the coding region, and (3) the 3'-untranslated region. The predicted amino acid sequence of the mature murine thrombospondin subunit is 95.1% identical to that of the human. The sequences of these two species are most similar at the regions containing the type 1, 2, and 3 repeats as well as the COOH-terminal globular domain. The thrombospondin promoter is similar to the 5' flanking region of some housekeeping and growth control genes in that it contains multiple GC-rich regions and lacks a CAAT box. The presence of various consensus sequences suggests that thrombospondin gene expression is regulated by cAMP, cytokines, and steroid hormones.