MAEA Human

MAEA was first identified and cloned by Hanspal et al. in 1998. The researchers cloned an MAEA cDNA from a human macrophage cDNA expression library using an antibody to the purified protein as a probe. The deduced protein consists of 395 amino acids and has a calculated molecular mass of 43 kD. However, recombinant protein and protein expressed by transfected COS-7 cells showed an apparent molecular mass of 36 kD by SDS-PAGE .

MAEA has a small N-terminal domain, a single transmembrane domain, and a large cytoplasmic domain containing several tyrosine residues. These tyrosine residues, when phosphorylated, can interact with protein recognition modules. MAEA is ubiquitously expressed in all tissues and cells examined, with two isoforms identified in macrophage membranes, having apparent molecular masses of 36 kD and 33 kD .

MAEA mediates the attachment of erythroblasts to macrophages, a process that is crucial for the survival and maturation of erythroblasts. This attachment is mediated by the extracellular N terminus of MAEA. The interaction between erythroblasts and macrophages prevents apoptosis in maturing erythroblasts, ensuring their proper development into mature red blood cells .

The erythroblastic island (EI), formed by a central macrophage and developing erythroblasts, plays a significant role in erythropoiesis. MAEA is suggested to mediate homophilic adhesion bonds bridging macrophages and erythroblasts. Studies have shown that MAEA-deficient mice die perinatally with anemia and defective erythrocyte enucleation, highlighting its critical role in fetal erythropoiesis .

Research on MAEA continues to uncover its various roles in erythropoiesis and its potential applications in medical science. For instance, conditional knockout mouse models have been used to assess the cellular and postnatal contributions of MAEA. These studies indicate that MAEA contributes to adult bone marrow erythropoiesis by regulating the maintenance of macrophages and their interaction with erythroblasts .