Kay M M, Bosman G, Johnson R C, Poulin J, Lawrence C, Goodman J
Department of Microbiology and Immunology, University of Arizona College of Medicine, Tucson 85724.
Exp Clin Immunogenet. 1994;11(4):209-21.
Band 3, the anion transporter, is a ubiquitous protein. It is present in brain and all other tissues. Not only is band 3 present in cell membranes, but also in nuclear, Golgi, and mitochondrion membranes. Band 3 is involved in respiration, acid-base balance, and is the major structural protein linking the plasma membrane to the cytoskeleton. Thus, alterations/mutations in the transport segment of the band-3 molecule might be expected to be of major importance. We discovered and sequenced a mutation of band 3, high-transport band 3 (HTbd3), that exhibits anion transport that is 2-3 time above normal. Anion transport studies of the family members revealed that red cells from the proposita, one of two siblings, and both parents had abnormally increased anion transport (increased Vmax). We used synthetic peptides of band 3 to help localize the change along the band-3 molecule. Results suggest that high-transport band 3 is altered in or near residue 869-883. This places the alteration toward the carboxyl terminal of band 3. cDNA sequencing demonstrated that the mutation was a proline to leucine at residue 868. A peptide was synthesized corresponding to residues 853-870 for testing in the anion transport inhibition assay. This peptide significantly inhibited anion transport (p < or = 0.001) indicating that it is an anion transport/binding region of band 3. Thus, DNA technology confirms the validity of the anion transport inhibition assay for localizing transport regions. Glucose transport is decreased in affected individuals. The HTbd3 mutation appears benign as determined by the red cell aging panel. IgG binding, creatinine, and glyceraldehyde-3-phosphate dehydrogenase are normal. Our studies indicate that the most rapid and sensitive techniques for detecting band-3 alterations are polyacrylamide gel electrophoresis, IgG binding, and anion transport studies. This is the only mutation of band 3 discovered to date the affects the transmembrane, anion transport region of band 3.
阴离子转运蛋白3（Band 3）是一种普遍存在的蛋白质。它存在于大脑和所有其他组织中。Band 3不仅存在于细胞膜中，还存在于核膜、高尔基体膜和线粒体膜中。Band 3参与呼吸作用、酸碱平衡，并且是将质膜与细胞骨架连接起来的主要结构蛋白。因此，Band 3分子转运区段的改变/突变可能具有重要意义。我们发现并测序了一种Band 3的突变体，即高转运Band 3（HTbd3），其阴离子转运能力比正常水平高2至3倍。对家庭成员的阴离子转运研究表明，先证者（两个兄弟姐妹之一）以及父母的红细胞阴离子转运异常增加（Vmax增加）。我们使用Band 3的合成肽来帮助确定沿Band 3分子发生变化的位置。结果表明，高转运Band 3在869 - 883位残基处或其附近发生了改变。这种改变位于Band 3的羧基末端附近。cDNA测序表明，该突变是868位残基处的脯氨酸突变为亮氨酸。合成了对应于853 - 870位残基的肽，用于阴离子转运抑制试验。该肽显著抑制了阴离子转运（p≤0.001），表明它是Band 3的一个阴离子转运/结合区域。因此，DNA技术证实了阴离子转运抑制试验用于定位转运区域的有效性。受影响个体的葡萄糖转运减少。根据红细胞老化检测结果，HTbd3突变似乎是良性的。IgG结合、肌酐和甘油醛 - 3 - 磷酸脱氢酶均正常。我们的研究表明，检测Band 3改变的最快速、灵敏的技术是聚丙烯酰胺凝胶电泳、IgG结合和阴离子转运研究。这是迄今为止发现的唯一影响Band 3跨膜阴离子转运区域的Band 3突变。
