Identification of three novel non-classical cadherin genes through comprehensive analysis of large cDNAs

The terminal sequences of long cDNAs from human brains were subjected to an improved method of motif-trap screening. This process resulted in the iden tification of three novel genes that encode proteins with 27, 27, and six c adherin domains that we denoted as KIAA1773, KIAA1774 and KIAA1775, respect ively. Sequence analysis indicated that the products of these genes were no n-classical cadherins. KIAA1773 was found to be a mammalian homologue of th e Drosophila dachsous gene but the remaining two genes did not have any lik ely homologues in public databases. Assessment of their expression in rat t issues indicated that these genes are expressed in highly distinct and tiss ue-specific patterns. Notably, KIAA1775 is expressed almost exclusively in the olfactory bulb in the rat brain. In situ hybridization further showed t hat KIAA1775 is strongly expressed by the mitral and tufted cells in the ma in and accessory olfactory bulbs, suggesting that KIAA1775 may be important in the formation and maintenance of neuronal networks, particularly those in the olfactory bulb. This study clearly shows the importance and usefulne ss of our cDNA project in search for genes encoding large proteins, as this project has allowed us to identify several novel non-classical cadherin ge nes that have thus far not been detected by conventional methods, (C) 2001 Elsevier Science BY All rights reserved.