Abstract
SHIP2 is a new member of the inositol polyphosphate 5-phosphatase family showing homology to SHIP1. The structure of both enzymes is characterized by the presence of a 5′ SH2 domain, a central catalytic domain, and a 3′ proline-rich region. Recent results suggest that SHIP2 and SHIP1 act downstream of various receptors by removing a phosphate from the 5′ position of the phosphatidylinositol 3′-kinase phosphatidylinositol 3,4,5-triphosphate product and of inositol 1,3,4,5-tetrakisphosphate. Human SHIP2 is highly expressed in adult heart, skeletal muscle, and placenta, whereas SHIP1 expression is limited to the hematopoietic system. We report here the molecular analysis of the mouse SHIP2 cDNA and the corresponding protein, the structure of the gene, and the identification of its promoter. SHIP2 mRNA expression was analyzed in embryonic and adult mouse tissues by reverse transcription–polymerase chain reaction and in situ hybridization. In embryonic day 15.5 mice, SHIP2 was strongly expressed in the liver, specific regions of the central nervous system, the thymus, the lung, and the cartilage perichondrium. In adult mice, SHIP2 mRNA was markedly present in the brain and the thymus and at different stages of spermatozoa maturation in the seminiferous tubules. The subtle differences in the protein structure of SHIP2 and SHIP1 as well as their different patterns of expression are discussed.
