Present in the thicker 16-17 nm junctions of mammalian lens fiber cells, where it may contribute to cell junctional organization. Acts as a receptor for calmodulin. May play an important role in both lens development and cataractogenesis. Seems to be associated with itself or another lens membrane component via disulfide bonds. Eye lens specific. Higher expression in lenses from pre-natal (1-5 months gestation) than those from postnatal (4-6 months) calves. Predominantly monophosphorylated on Ser-170. Only about 15% diphosphorylated on both Ser-170 and Thr-171. C-glycosylated. Trp-43 is more extensively C-glycosylated than Trp-61. C-glycosylation may be involved in membrane trafficking. Belongs to the PMP-22/EMP/MP20 family.