Molecular cloning and characterization of CDEP, a novel human protein containing the ezrin-like domain of the band 4.1 superfamily and the Dbl homology domain of Rho guanine nucleotide exchange factors.

A cDNA for a novel human protein named CDEP was cloned using the subtractive hybridization method between dedifferentiated cartilage cells and overtly differentiated cartilage cells. CDEP cDNA contained an open reading frame encoding 1,045 amino acids in a total length of 3.4 kb. The deduced amino acid sequence revealed that a single polypeptide contained the ezrin-like domain, which is found in cytoskeleton-associated proteins of the band 4.1 superfamily, and the Dbl homology (DH) and pleckstrin homology (PH) domains, which are conserved in the Rho GEF (guanine nucleotide exchange factor) family. Northern blot analysis demonstrated that CDEP mRNA was expressed not only in the differentiated chondrocytes but also in various fetal and adult tissues. Since members of the band 4.1 superfamily and the Rho GEF family are crucial for microfilament organization, the novel protein CDEP may be involved in the adhesion, proliferation, and differentiation of some cell types including chondrocytes via changes in the cytoskeleton.