A molecular defect of spectrin in a subset of patients with hereditary elliptocytosis. Alterations in the alpha-subunit domain involved in spectrin self-association.

A B S T R A C T The structural and functional properties of spectrin from normal and hereditary pyropoikilocytosis (HPP) donors from the two unrelated families were studied. The structural domains of the spectrin molecule were generated by mild tryptic digestion and analyzed by two-dimensional electrophoresis (isoelectric focusing; sodium dodecyl sulfate-polyacrylamide gel electrophoresis). The aI-T80 peptide (Mr 80,000) is not detectable in two related HPP donors; instead, two new peptides (Mr 50,000 and 21,000) are generated and have been identified as fragments of the normal aI-T80. A third sibling has reduced levels of both the normal aI-T80 and the two new peptides.A similar analysis of spectrin from another HPP family indicates that their spectrins contain reduced amounts of the aI-T80 and the 50,000 and 21,000 fragments of the aI domain. The HPP donor also has other structural variations in the al, aIl, and alII domains.The aI-T80 domain of normal spectrin has been shown to be an important site for spectrin oligomerization (J. Morrow and V. T. Marchesi. 1981. J. Cell Biol. 88: 463-468), and in vitro assays indicate that HPP spectrin has an impaired ability to oligomerize. Ghost membranes from HPP donors are also more fragile than membranes from normal erythrocytes when measured by ektacytometry. In both the oligomerization and fragility assays, the degree of impairment is correlated with the amount of normal aI-T80 present in the spectrin molecule.A preliminary report of this work was presented at an ICN/UCLA Symposium, Keystone, CO, 18 February 1981.

Section: Discussionsupporting

confidence: 85%

Molecular and functional changes in spectrin from patients with hereditary pyropoikilocytosis.

Knowles¹,

Morrow²,

Speicher³

et al. 1983

“…Several previous studies of spectrin from individuals with hereditary elliptocytosis and hereditary pyropoikilocytosis have correlated defective dimer-dimer association with changes in the digestion pattern of one of the domains responsible for that function, the alpha I-T80 (32)(33)(34)(35)(36)(55)(56)(57)(58). In contrast, similar alterations in the spectrin domain map have not been reported in the autosomal dominant form of HS.…”

Section: Discussionmentioning

confidence: 80%

“…1) described by Wolfe and co-workers (29). Tryptic digestion with peptide analysis has been used to demonstrate the structural abnormalities of spectrin in hereditary elliptocytosis and hereditary pyropoikilocytosis (32)(33)(34)(35)(36), but this method has thus far failed to demonstrate abnormal structure of spectrin in most patients with HS. However, by studying the kinetics of enzymatic digestion, we were able to obtain evidence for aberrant structure of spectrin in HS in the region of the beta IV-T74 domain.3 This area coincides with the location of the presumed protein 4.1 binding site: the end of spectrin opposite to the oligomerization site (38), probably the beta-chain (39,40).…”

Section: Introductionmentioning

confidence: 99%

Abnormal oxidant sensitivity and beta-chain structure of spectrin in hereditary spherocytosis associated with defective spectrin-protein 4.1 binding.

Becker¹,

Morrow²,

Lux³

1987

Hereditary spherocytosis (HS) is an inherited disorder of erythrocyte shape associated with spectrin deficiency and hemolytic anemia. In a subset of patients with the autosomal dominant form of HS, spectrin displays a reduced capacity to bind protein 4.1 and, therefore, actin; both functions that are critical to the membrane skeleton. A specific structural defect has not been identified in the spectrin from these patients. Chymotryptic digestion of the isolated spectrin chains shows impaired cleavage of the distal peptide of the beta subunit, the beta IV domain. In previous work, we have shown that mild oxidation markedly diminishes the binding capacity of normal spectrin for protein 4

“…1. Family 6 is one of the two original black American kindred in whom the Sp a1174 defect was first detected (24) and clinical and protein data on family 4 have been reported previously (25 Erythrocyte membrane protein analysis. The methods used have been previously referred to or described in detail (24,26,27).…”

Section: Methodsmentioning

confidence: 99%

Four different mutations in codon 28 of alpha spectrin are associated with structurally and functionally abnormal spectrin alpha I/74 in hereditary elliptocytosis.

Coetzer¹,

Sahr²,

Prchal³

et al. 1991

Self Cite

IntroductionHereditary elliptocytosis (HE) Sp aoP4 is a disorder associated with defective spectrin (Sp) heterodimer self-association and an abnormal tryptic cleavage of the 80-kD aI domain of Sp resulting in increased amounts of a 74-kD peptide. The molecular basis of this disorder is heterogeneous and mutations in codons 28, 46, 48, and 49 (codons 22, 40, 42, and 43 in the previous nomenclature which did not include the six NH2-terminal amino acids) have been reported. In this study we present data on seven unrelated HE Sp all4 kindred from diverse racial backgrounds in whom we identified four different mutations all occurring in exon 2 of a Sp at codon 28. Utilizing the polymerase chain reaction we established a CGT 7CTT; Arg --Leu 28 mutation in one kindred of Arab/Druze origin. In two unrelated white kindred of English/European origin the substitu-