Band 4.2, which plays an important but poorly understood role in erythrocyte function and survival, is a major component of erythrocyte membranes. Recently, it has been shown that the gene for murine protein band 4.2 colocalizes on chromosome 2 with the murine pallid mutation, which affects the formation or function of intracellular storage granules in melanocytes and platelets and lysosomes in kidney. As a first step in identifying the mutation responsible for the pallid phenotype, we have sequenced the entire normal murine band 4.2 gene. Our results show that the gene for murine band 4.2 is approximately 22 kb in size, with 13 exons and 12 intervening introns. The organization of the mouse band 4.2 gene is identical to that of the human band 4.2 gene and similar to that of the genes for the transglutaminase enzymes, reiterating the membership of protein band 4.2 in the transglutaminase gene superfamily. We also present 3.5 kb of normal murine erythroid band 4.2 cDNA sequence containing an open reading frame of 2073 bp and coding for 691 amino acids. This is the same size as the human erythrocyte protein, with which the murine protein shares a 72% amino acid identity.