Björk J, Reardon D M, Backman L
Department of Biochemistry, Umeå University, Sweden.
Biochim Biophys Acta. 1997 Jun 12;1326(2):342-8. doi: 10.1016/s0005-2736(97)00037-0.
Metabolic depletion of hereditary ovalocytes leads, similar to normal red cells, to decreased intracellular concentrations of ATP and GSH as well as degradation of the phosphoinositides to phosphatidylinositol and diacylglycerol. In contrast to normal red cells, however, loss of ATP does not induce any gross shape transformations; even after extensive depletion the ovalocytes retain their initial elongated stomatocytic character. The mechanical properties of hereditary ovalocytes are associated with a deletion of nine amino acid residues in band 3. Since the deletion appears to increase the stiffness of a normally flexible region of band 3, connecting the N-terminal cytoplasmic domain with the membrane spanning domain, our results indicate that shape changes require a flexible attachment of the cytoskeleton to the membrane-spanning band 3. The results also imply that metabolism of phosphoinositide cannot be the only determinant of cell shape, as suggested by the bilayer-couple hypothesis, but also other factors are involved in metabolically induced shape transformations.
遗传性椭圆形红细胞的代谢耗竭，与正常红细胞类似，会导致细胞内ATP和谷胱甘肽（GSH）浓度降低，以及磷酸肌醇降解为磷脂酰肌醇和二酰甘油。然而，与正常红细胞不同的是，ATP的丧失不会引起任何明显的形态转变；即使在大量耗竭后，椭圆形红细胞仍保持其最初的细长口形细胞特征。遗传性椭圆形红细胞的力学特性与带3中九个氨基酸残基的缺失有关。由于该缺失似乎增加了带3正常柔性区域的硬度，该区域连接N端细胞质结构域和跨膜结构域，我们的结果表明，形状变化需要细胞骨架与跨膜带3的柔性连接。结果还暗示，如双层偶联假说所提出的，磷酸肌醇的代谢不能是细胞形状的唯一决定因素，代谢诱导的形状转变还涉及其他因素。
