This ENU-induced mutation was isolated in a screen at the University of Pittsburgh. The molecular lesion is an A to G substitution at coding nucleotide 3247 in exon 28 of the cDNA (NM_134013:c.A3247G). This changes the isoleucine residue to valine at position 1083 of the encoded protein (p.I1083V). (J:175213) Additional incidental mutations were detected in sequencing for the causative mutation, Psme4b2b1508Clo, and may be present in stocks carrying this mutation.