Genotypic and phenotypic expressions of protein 4.2 in human erythroid cells

Abstract

Protein 4.2 (P4.2) is one of the major red cell membrane proteins, which binds to the membrane skeletal network and to the cytoplasmic domain of anion exchanger band 3, and also interacts with ankyrin. P4.2 plays an important role in maintaining the stability and flexibility of red cells by these biophysical functions. Patients with P4.2 deficiency in their red cell membranes suffer from congenital hemolytic anemia with microspherocytosis or the like. Therefore, new information on the structure and function of the P4.2 gene, characteristics of protein 4.2, and the localization of this protein in the red cell membrane ultrastructure are reviewed. Expression of the gene and protein 4.2 in erythroid and non-erythroid tissues is discussed. In addition, the genotype and phenotype of protein 4.2 deficiency are described in humans and in the targeted P4.2 knock-out (4.2^−/−) mice.