CDNA SEQUENCE-ANALYSIS, CHROMOSOMAL ASSIGNMENT AND EXPRESSION PATTERNOF THE GENE CODING FOR INTEGRAL MEMBRANE-PROTEIN 2B

The complete cDNA of the mouse integral membrane protein 2B gene (Itm2 b) was determined by sequence analysis of expressed sequence tag (EST) clone L26775 and a clone isolated from a cDNA library of the osteogen ic stromal cell line MN7 (Mathieu et al., 1992. Calcif. Tissue Int. 50 , 362-371) and by 5' rapid amplification of cDNA ends (RACE). Alignmen t of different mouse ESTs confirmed the entire sequence. Northern blot analysis of different neonatal and adult mouse tissues showed that It m2b is ubiquitously expressed. There are three mRNAs with different le ngths in neonatal as well as in adult tissues, originating from altern ative polyadenylation by usage of one consensus and two additional var iant polyadenylation signals. The cDNA sequence of the human Itm2b hom olog (ITM2B) was assembled using data from available human ESTs. Both the mouse and the human gene code for a protein of 266 amino acids (aa ) that is homologous to a previously described integral membrane prote in, Itm2A, of which the expression is restricted to osteo- and chondro genic tissues. Itm2A and Itm2B belong to a family of type II integral membrane proteins, which contains a third member, Itm2C (Deleersnijder et al., 1996. J. Biol. Chem. 271, 19475-19482). The human ITM2B and m ouse Itm2b genes were previously mapped as unknown ESTs to conserved s yntenic regions Home sapiens 13q12-13 and Mus musculus 14. (C) 1998 El sevier Science B.V. All rights reserved.