MAK and retinitis pigmentosa: Taken at face value, such changes would be expected to result in loss of catalytic activity, and in fact mutation of the equivalent residue, Asn130, in the male germ cell-associated kinase MAK has been shown to cause complete loss of kinase activity, resulting in retinitis pigmentosa.13 However, given that the results of modelling in Swiss-Model suggested ligand binding is unfavourable in the Asn842Ser variant, the structure of the ligand binding pocket was examined in more detail.