Assignment1 of the neuronal cochaperone, HSJ1, to human chromosome bands 2q32→q34 between D2S295 and D2S339 by in situ hybridization and somatic cell and radiation hybrids

Molecular chaperones of the Hsp70 family facilitate many fundamental cellular processes. Hsp70 function is regulated by cochaperones, such as the DnaJ family that regulate Hsp70 ATP hydrolysis and substrate binding (Cheetham and Caplan, 1998). We have previously identified a human DnaJ-like protein, HSJ1, that is expressed preferentially in brain, encoded by a single copy gene and alternatively spliced to produce two isoforms that regulate the function of Hsp70 (Cheetham et al., 1992; Cheetham et al., 1994; Cheetham et al., 1996). BLAST analysis of the Genbank database highlighted a putative transcript from chromosome 6 as being identical to the first 232 bp of HSJ1. This transcript ORF GT260 (Totaro et al., 1996; Accession X90535) had been assigned to 6p21.3. In this study, we report the assignment of HSJ1 using somatic cell hybrids, radiation hybrids and FISH to chromosome 2 and find no evidence to link HSJ1 to chromosome 6. Further analyses of the GT 260 sequence showed that bases 75–306 corresponded to HSJ1, whereas bases 312–968 are identical to another gene, FB19 (Accession Y13247), in the opposite orientation. This suggests that the two genomic bands identified by probing with GT 260 (Totaro et al., 1996) may correspond to HSJ1 on chromosome 2 and FB19 on chromosome 6, and that GT 260 is a cloning artefact. Materials and methods