Protamine 2 (PRM2)

Presumably PRM2 is located on human chromosome 16, close to PRM1: in the mouse the corresponding 2 loci are closely linked, and in the Chinese hamster, probes specific for the 2 protamines hybridize to the same restriction fragments after digestion of hamster genomic DNA with any of 5 different restriction endonucleases (Reeves et al., 1987, 1989). The tight linkage may be of functional significance since PRM1 and PRM2 are among the limited number of genes known to be expressed postmeiotically in haploid cells.

In mouse, only one P2 protamine has been detected, whereas in man, the P2 protamine family is represented by 3 protamines, HP2, HP3 and HP4, whose amino acid sequences are identical except at their amino terminal ends .