TOM1 genes map to human chromosome 22q13.1 and mouse chromosome 8C1 and encode proteins similar to the endosomal proteins HGS and STAM

The avian tom1 (target of myb 1) gene has been previously characterized fro m v-myb-transformed cells. We report here cloning of the human and mouse to m1 orthologs. Both genes are expressed ubiquitously, with the highest level s in skeletal muscle, brain, and intestines, as assessed by Northern blot a nd mRNA in situ hybridization. The N-terminal domain of the TOM1 protein sh ares similarity with HGS (hepatocyte growth factor-regulated tyrosine kinas e substrate) and STAM (signal-transducing adaptor molecule), which are asso ciated with vesicular trafficking at the endosome, A putative coiled-coil d omain was also detected in the central part of the TOM1 protein. This domai n structure suggests that TOM1 is another member of a family of genes impli cated in the trafficking regulation of growth-factor-receptor complexes tha t are destined for degradation in the lysosome, We also show that a human p aralog of TOM1 (TOM1-like gene I) exists. Furthermore, we provide a transcr iption map over a 190-kb contig of the TOM1 region. This map includes its d istal neighbors HMOX1 and MCM5 and two proximal novel genes, one of which i s a HMG-box-containing gene (HMG2L1), and the other of unknown function. Us ing a genomic PAC clone, we demonstrate that the mouse Tom1 and Hmox1 genes are part of an as yet undescribed syntenic group between mouse chromosome 8C1 and human chromosome 22q13.1, (C) 1999 Academic Press.