OCP1, an F-box protein, co-localizes with OCP2/SKP1 in the cochlear epithelial gap junction region

Immunohistochemical data indicate that OCP1 co-localizes exactly with OCP2 in the epithelial gap junction region or the guinea pig organ of Corti (OC) . Despite the abundance of OCP1 in the OC, gaining access to its coding seq uence - and, in particular, the 5' end of the coding sequence - proved unex pectedly challenging. The putative full-length OCP1 cDNA - 1180 nucleotides in length - includes a 67 nucleotide 5' leader sequence, 300 codons (inclu ding initiation and termination signals), and a 216 nucleotide 3' untransla ted region. The cDNA encodes a protein having a predicted molecular weight of 33 700. The inferred amino acid sequence harbors an F-box motif spanning residues 52-91, consistent with a role for OCP1 and OCP2 in the proteasome -mediated degradation of select OC proteins. Although OCP1 displays extensi ve homology to an F-box protein recently cloned from rat brain (NFB42), clu stered sequence non-identities indicate that the two proteins are transcrib ed from distinct genes. The presumptive human OCP1 gene was identified in t he human genome databank. Located on chromosome 1p35. the inferred translat ion product exhibits 94% identity with the guinea pig OCP1 coding sequence. (C) 2001 Elsevier Science B.V. All rights reserved.