Structural studies on the effects of the deletion in the red cell anion exchanger (band 3, AE1) associated with South East Asian ovalocytosis.
J Mol Biol
; 285(3): 1289-307, 1999 Jan 22.
Article
em En
| MEDLINE
| ID: mdl-9887277
ABSTRACT
We have carried out a solution-state NMR study of synthetic peptides patterned on the first membrane span of normal human band 3, and the same region of the mutant band 3 present in Southeast Asian ovalocytosis (SAO) which has a nine amino acid deletion. In 11 (v/v) chloroform/methanol, the 42 residue normal peptide (R389-K430) consisted of three helical regions. The slow solvent exchange of backbone amide protons revealed the helix from P403 to A416 was more stable than the "cytoplasmic" N-terminal helix from P391 to A400. These helices were separated by a sharp bend at P403, which is probably located at the boundary between the cytoplasmic domain and the first transmembrane span. The SAO deletion (A400-A408) removed the bend at P403, to leave a stable helix from P391 to A416 containing the residuum of the normal first transmembrane helix and with a hydrophobic turn replaced by a polar turn in the SAO peptide. Insertion of fragments of normal band 3 and band 3 SAO into microsomal membranes was investigated using a cell free translation system. A fragment composed of the cytoplasmic domain and the putative first membrane domain of normal band 3 (B3(1)) inserted stably into the membrane. However, the corresponding fragment of band 3 SAO [SAO(1)] did not integrate stably into membranes. Our results suggest that in SAO band 3, the region of the first membrane span of normal band 3 does not integrate properly into the membrane because it lacks a sufficiently long hydrophobic segment, and the deletion also disrupts a conserved structural subdomain at the membrane surface.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteína 1 de Troca de Ânion do Eritrócito
/
Eliptocitose Hereditária
Tipo de estudo:
Risk_factors_studies
Limite:
Humans
País/Região como assunto:
Asia
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article