Cloning of a hsp70-related gene expressed in mouse spermatids

A cDNA library of spermatids was screened by a differential hybridization in order to isolate genes expressed in haploid cells of the mouse male germ line. A clone was found that encoded a protein related to the heat shock protein 70. A genomic DNA clone comparable to this cDNA clone was also isolated from a mouse genomic library. This gene had only one continuous open reading frame capable of coding a 630 amino-acid protein. There was an excellent match of the sequence with the heat shock protein 70 family but a difference from any previous 70 kilodalton heat shock protein. A 2.7kb transcript derived from this gene was expressed in spermatids but not in other testicular germ cells and somatic tissues. We have referred to this gene as hsc70t.