Nesprin 3 (Nesp3)

Nesprin-3 encodes a type II transmembrane protein that contains a C-terminal KASH domain and a series of spectrin repeats (SR). Orthologs were identified in human, rat, chimpanzee, dog, and chicken. Two splice variants, nesprin-3a and nesprin-3b, were identified in mouse. Nesprin-3a, the longer variant, is predicted to be 975 amino acids, has a molecular mass of about 108 kD, and contains 8 SRs. It has a different N-terminal sequence than nesprin-3b, which is predicted to be 888 amino acids, has a molecular mass of about 99 kD, and contains 7 SRs, missing the first SR of nesprin-3a. Immunofluorescence studies found that nesprin-3 is a component of the nuclear envelope, and electron microscopy revealed that, like nesprin-1 and nesprin-2, nesprin-3 is present in the outer nuclear membrane (ONM).