The Chediak-Higashi syndrome is characterized by partial albinism and recurrent infections with giant granules in granulocytes. This syndrome has been proposed to have a defect in vesicular transport. Rab 4 is a member of a family of Ras-related small GTP-binding proteins, which has been mapped in the locus of the Chediak-Higashi syndrome. We isolated a full length cDNA of rab 4 from a cDNA library of mouse liver. The clone is 1428 base pairs (bp) in length and contains a 639 bp open reading frame encoding a polypeptide of 213 residues. The deduced amino acid sequence is highly homologous to rab 4 from rat and human. We analyzed rab 4 as a candidate gene of the beige mouse, but we could not find any change in the sequence of the coding region of rab 4 mRNA.