Disease:Defects in EPB41 are a cause of hereditary pyropoikilocytosis (HPP) [MIM:266140]. HPP is an autosomal recessive hematologic disorder characterized by hemolytic anemia , microspherocytosis , poikilocytosis , and an unusual thermal sensitivity of red cells. ,Disease:Defects in EPB41 are the cause of elliptocytosis type 1 (EL1) [MIM:611804]. EL1 is a Rhesus-linked form of hereditary elliptocytosis , a genetically heterogeneous , autosomal dominant , hematologic disorder. It is characterized by variable hemolytic anemia and elliptical or oval red cell shape. ,Function:Protein 4.1 is a major structural element of the erythrocyte membrane skeleton. It plays a key role in regulating membrane physical properties of mechanical stability and deformability by stabilizing spectrin-actin interaction. Recruits DLG1 to membranes. ,PTM:O-glycosylated; contains N-acetylglucosamine side chains in the C-terminal domain. ,PTM:Phosphorylated at multiple sites by different protein kinases and each phosphorylation event selectively modulates the protein's functions. ,PTM:Phosphorylation on Tyr-660 reduces the ability of 4.1 to promote the assembly of the spectrin/actin/4.1 ternary complex. ,similarity:Contains 1 FERM domain. ,subunit:Binds with a high affinity to glycophorin and with lower affinity to band III protein. Associates with the nuclear mitotic apparatus. Binds calmodulin , CENPJ and DLG1. Also found to associate with contractile apparatus and tight junctions. ,
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