USH1C contains an N-terminal domain followed by 2 PDZ domains; a coiled-coil region with a bipartite nuclear localization signal; a PEST degradation sequence; a third PDZ domain; and a C-terminal domain. PDZ73 also has an N-glycosylation site and 17 putative phosphorylation sites. One variant encodes a deduced 403-amino acid protein with a calculated molecular mass of about 45 kD. This variant lacks the C-terminal half of the full-length protein, including the PEST sequence, the third PDZ domain, and the C-terminal region. Another variant, which predominates in brain, encodes a putative 328-amino acid protein with a calculated molecular mass of about 37 kD. This variant lacks the N-terminal half of the full-length protein and begins with part of the coiled-coil domain.