Molecular biochemistry and electron microscopy in normal and abnormal human red cell membrane protein 4.2

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The following results were obtained for the recent two years (1995-1997)1. Protein band 4.2 (P4.2) anomalies in hereditary hemolyic anemia(1) Complete P4.2 deficiency type(1) P4.2 gene mutations :Two novel mutations were detected : Allele Komatsu (523GAT*TAT) and allele Shiga (317CGC*TGC).Marked derangements were observed on the intramembrane particles and the cytoskeletal network in two types by electron microscopy.(2) Protein band 3 (B3) gene mutations :Two novel mutations were detected ; First, allele Okinawa (G714R) with Memphis II polymorphism (K56E+P854L) and allele Fukuoka (G130R) in compound heterozygous state. It was indicated that these mutations resulted to complete P4.2 protein deficiency with marked decrease of B3 protein.Secondly, a combined deficiency of P4.2 and B3 proteins was described as the first case in the world. The B3 gene analysis showed a C*T nucleotide substitution resulting in a nonsense mutation to codon 646.(2) Partial P4.2 deficiency typeMost cases of thi … More s type were found in hereditary spherocytosis (HS) with partial B3 deficiency.30 HS cases were analyzed on the B3 genes by the method of PCR/SSCP.Four mutations were detected in 5,12,17 and 19th exons of the B3 genes.(3) P4.2 variant typeThe pathogenesis of P4.2 doublet Nagano (72/74kD) was studied by biochemistry and molecular biology.A novel mutation was detected in exon 10 at 1463nt (R488H) of the P4.2 gene in heterozygous state.2. Morphogenesis of red cell membranes(1) Protein expression in human erythroblastsIt was shown that the expression of membrane proteins in erythroid differentiation was initiated in spectrins, glycophorins and band 3, followed by protein 4.1 and ankyrin, and completed by the expression of protein 4.2 at the latest stage of the differentiation.(2) Physiological functions of P4.2 proteinBiochemical and immunoelectron microscopic studies showed the posibility that P4.2 protein might play a role in connecting the spectrin network to B3 protein as a kind of anchoring protein. Less