The mutation in the loop tail mouse is a transition point mutation that alters a G to an A at coding nucleotide 1391 (c.1391G>A). This is predicted to alter serine 464 to asparagine (p.S464N) in the encoded protein. Western blot analysis indicates an approximate 80% reduction in protein expression in homozygotes and downward shift in molecular mass that is emulated by dephosphorylation of the wild-type protein. (J:52606, J:70272, J:211696, J:216413)