Gallagher P G, Romana M, Lieman J H, Ward D C
Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06510, USA.
Blood. 1995 Jul 1;86(1):359-65.
Band 7.2b is an integral phosphoprotein absent from the erythrocyte membranes of patients with hydrocytosis, an autosomal, dominantly inherited, hemolytic anemia characterized by stomatocytic red blood cells with abnormal permeability to Na+ and K+. The role of this protein in the erythrocyte membrane is not well understood. To gain additional insight into the structure and function of this protein, we have cloned the murine band 7.2b cDNA and studied its tissue-specific expression. 2,873 bp of cDNA with an open reading frame of 852 bp were isolated. This fragment encodes a protein of 284 amino acids with a predicted molecular weight of 31 kD. The band 7.2b gene had a wide pattern of expression, with high levels of mRNA in heart, liver, skeletal muscle, and testis and low levels in lung, brain, and spleen. Using fluorescent in situ hybridization, the murine band 7.2b gene was mapped to chromosome 2, at the border of the distal region of 2B and proximal region of C1, syntenic to 9q33-q34, the location of the human homologue. Models of the predicted protein structure showed a short NH2-terminal head, a strongly hydrophobic 28-amino acid stretch presumably encoding a single membrane-spanning domain, and a large domain composed of beta sheet and alpha helix. Database searching showed no significant homology of other known proteins to murine or human band 7.2b.
7.2b带是一种整合磷蛋白，在水细胞增多症患者的红细胞膜中不存在。水细胞增多症是一种常染色体显性遗传的溶血性贫血，其特征是口形红细胞对Na+和K+具有异常通透性。该蛋白在红细胞膜中的作用尚不清楚。为了进一步深入了解该蛋白的结构和功能，我们克隆了小鼠7.2b带cDNA并研究了其组织特异性表达。分离出了2873 bp的cDNA，其开放阅读框为852 bp。该片段编码一个由284个氨基酸组成的蛋白质，预测分子量为31 kD。7.2b带基因具有广泛的表达模式，在心脏、肝脏、骨骼肌和睾丸中mRNA水平较高，而在肺、脑和脾脏中水平较低。使用荧光原位杂交技术，将小鼠7.2b带基因定位到2号染色体上，位于2B远端区域和C1近端区域的边界，与人类同源物的位置9q33 - q34同线。预测的蛋白质结构模型显示有一个短的NH2末端头部、一个可能编码单个跨膜结构域的28个氨基酸的强疏水片段以及一个由β折叠和α螺旋组成的大结构域。数据库搜索显示，其他已知蛋白质与小鼠或人类7.2b带没有显著同源性。
