| Summary: | Human erythrocytes are highly specialised cells boasting numerous features to maximise gas carriage, exchange and delivery around the body. The role of the highly proteinaceous red cell membrane in these processes is vital. Some membrane proteins such as the Rh-associated glycoprotein (RhAG) and aquaporin-1 (AQP1) are postulated to form gas channels, and disorders affecting membrane proteins can have extensive effects on normal red cell function. In this work, the role and interactions of Rh proteins are probed using rare variant Rh-deficient erythrocytes. The RhCE polypeptide is required for normal expression of other members of the Rh complex. Lack of RhCE is associated with depressed expression of CD44, an adhesion molecule, and may alter expression of proteins involved in complement such as decay acceleration factor and Iymphocyte function-associated antigen 3. Absence of RhAG prevents Rh complex expression and is found to affect band 3 macrocomplex proteins GPA and protein 4.2, highlighting the important role for RhAG in the macrocomplex. AQP1 is increased in the absence of RhAG, which supports the hypothesis that they share similar functions. The hereditary stomatocytoses are disorders that affect the ion permeability of red cell membranes. This work comprises a study of the pleiotropic disorder stomatin-deficient cryohydrocytosis (sdCHC), which is caused by mutations in the red cell glucose transporter, glut1. The mutant proteins show minimal glucose transport and increased permeability to cations when expressed heterologously in Xenopus laevis oocytes - consistent with the disease phenotype. sdCHC erythrocytes have very reduced amounts of stomatin, a monotopic membrane protein, a feature shared by other very leaky red cells. This is accompanied by a concomitant increase in stomatin-like protein 2, whose function in red cells is currently unknown. The fates of stomatin proteins in normal and leaky cells are investigated throughout erythropoiesis and found to differ between cation-leaky phenotypes.
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