Genomic sequences of human protamines whose genes, PRM1 and PRM2, are clustered

Protamines are small, arginine-rich proteins involved in the condensation of sperm chromatin. Using cDNA clones, we have isolated the genes for both human protamines, i.e., protamine 1 (PRM1) and protamine 2 (PRM2), from a human cosmid library. Each of these genes contains a single intron consisting of 91 and 163 bp, respectively. From the 5'-noncoding region of PRM1 664 bp and from the 5'-noncoding region of PRM2 902 bp were determined. Both genes contain typical TATAA and CAAT boxes at conventional distances from the transcription start points, which by using primer extension experiments could be assigned to nucleotides -91 and -110 for PRM1 and PRM2 genes, respectively. Comparison of the 5'-noncoding regions of PRM1 and PRM2 genes reveals 12 different motifs in common, 8 of which are clustered in both genes and could reflect regulatory elements for testis- and spermatid-specific gene expression. Both human genes have been found to be clustered at a distance of 4.8 kb. Comparison of the genomic organization of human and mouse protamine genes revealed greater similarities between the two in the 5'-noncoding region.