Interactions between mutant and wild-type band 3 subunits in hereditary Southeast Asian ovalocytic red blood cell membranes

James M. Salhany, Lawrence M Schopfer

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Red cell membranes from individuals with Southeast Asian ovalocytosis (SAO) contain approximately equal proportions of wild-type band 3 and a mutant SAO band 3 which lacks residues 400-408. It is known that the V(max) for anion exchange in SAO cells is reduced by about 50%, that SAO band 3 does not transport anions when expressed alone in a cellular expression system, that SAO band 3 does not bind stilbenedisulfonates, and that about 50% of the band 3 exists as wild-type/SAO heterodimers. In this report, we show that the kinetics of H2DIDS (4,4'-diisothiocyanatodihydro-2,2'-stilbenedisulfonate) release from the wild-type band 3 in SAO membranes is biphasic. The two phases were present in about equal proportions, with rate constants differing by about 5-fold. In contrast, control cells showed monophasic, exponential kinetics with a rate constant comparable to that of the fast phase of SAO membranes. We assign the fast phase in SAO membranes to H2DIDS release from wild-type subunits within homodirects and the slow phase to H2DIDS release from the wild-type subunit within the heterodimer. No differences were observed in kinetic studies of H2DIDS binding. These results suggest that the mutant band 3 subunit alters the conformation of its neighboring wild- type subunit within the heterodimer, resulting in about a 4-fold higher H2DIDS affinity. Additional evidence suggesting that the interactions in the heterodimer may be confined to a region of the wild-type subunit containing the C-terminal subdomain is presented. The relationship of these subunit interactions to the observation of a reduced cellular anion transport function is discussed.

Original languageEnglish (US)
Pages (from-to)251-257
Number of pages7
JournalBiochemistry
Volume35
Issue number1
DOIs
StatePublished - Jan 9 1996

Fingerprint

Cell membranes
Blood
Erythrocytes
Cell Membrane
Anions
Membranes
Kinetics
Rate constants
Conformations
Observation
dihydro-DIDS

ASJC Scopus subject areas

  • Biochemistry

Cite this

Interactions between mutant and wild-type band 3 subunits in hereditary Southeast Asian ovalocytic red blood cell membranes. / Salhany, James M.; Schopfer, Lawrence M.

In: Biochemistry, Vol. 35, No. 1, 09.01.1996, p. 251-257.

Research output: Contribution to journalArticle

@article{450584b90a12418f9f9f58142eec3839,
title = "Interactions between mutant and wild-type band 3 subunits in hereditary Southeast Asian ovalocytic red blood cell membranes",
abstract = "Red cell membranes from individuals with Southeast Asian ovalocytosis (SAO) contain approximately equal proportions of wild-type band 3 and a mutant SAO band 3 which lacks residues 400-408. It is known that the V(max) for anion exchange in SAO cells is reduced by about 50{\%}, that SAO band 3 does not transport anions when expressed alone in a cellular expression system, that SAO band 3 does not bind stilbenedisulfonates, and that about 50{\%} of the band 3 exists as wild-type/SAO heterodimers. In this report, we show that the kinetics of H2DIDS (4,4'-diisothiocyanatodihydro-2,2'-stilbenedisulfonate) release from the wild-type band 3 in SAO membranes is biphasic. The two phases were present in about equal proportions, with rate constants differing by about 5-fold. In contrast, control cells showed monophasic, exponential kinetics with a rate constant comparable to that of the fast phase of SAO membranes. We assign the fast phase in SAO membranes to H2DIDS release from wild-type subunits within homodirects and the slow phase to H2DIDS release from the wild-type subunit within the heterodimer. No differences were observed in kinetic studies of H2DIDS binding. These results suggest that the mutant band 3 subunit alters the conformation of its neighboring wild- type subunit within the heterodimer, resulting in about a 4-fold higher H2DIDS affinity. Additional evidence suggesting that the interactions in the heterodimer may be confined to a region of the wild-type subunit containing the C-terminal subdomain is presented. The relationship of these subunit interactions to the observation of a reduced cellular anion transport function is discussed.",
author = "Salhany, {James M.} and Schopfer, {Lawrence M}",
year = "1996",
month = "1",
day = "9",
doi = "10.1021/bi952411b",
language = "English (US)",
volume = "35",
pages = "251--257",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "1",

}

TY - JOUR

T1 - Interactions between mutant and wild-type band 3 subunits in hereditary Southeast Asian ovalocytic red blood cell membranes

AU - Salhany, James M.

AU - Schopfer, Lawrence M

PY - 1996/1/9

Y1 - 1996/1/9

N2 - Red cell membranes from individuals with Southeast Asian ovalocytosis (SAO) contain approximately equal proportions of wild-type band 3 and a mutant SAO band 3 which lacks residues 400-408. It is known that the V(max) for anion exchange in SAO cells is reduced by about 50%, that SAO band 3 does not transport anions when expressed alone in a cellular expression system, that SAO band 3 does not bind stilbenedisulfonates, and that about 50% of the band 3 exists as wild-type/SAO heterodimers. In this report, we show that the kinetics of H2DIDS (4,4'-diisothiocyanatodihydro-2,2'-stilbenedisulfonate) release from the wild-type band 3 in SAO membranes is biphasic. The two phases were present in about equal proportions, with rate constants differing by about 5-fold. In contrast, control cells showed monophasic, exponential kinetics with a rate constant comparable to that of the fast phase of SAO membranes. We assign the fast phase in SAO membranes to H2DIDS release from wild-type subunits within homodirects and the slow phase to H2DIDS release from the wild-type subunit within the heterodimer. No differences were observed in kinetic studies of H2DIDS binding. These results suggest that the mutant band 3 subunit alters the conformation of its neighboring wild- type subunit within the heterodimer, resulting in about a 4-fold higher H2DIDS affinity. Additional evidence suggesting that the interactions in the heterodimer may be confined to a region of the wild-type subunit containing the C-terminal subdomain is presented. The relationship of these subunit interactions to the observation of a reduced cellular anion transport function is discussed.

AB - Red cell membranes from individuals with Southeast Asian ovalocytosis (SAO) contain approximately equal proportions of wild-type band 3 and a mutant SAO band 3 which lacks residues 400-408. It is known that the V(max) for anion exchange in SAO cells is reduced by about 50%, that SAO band 3 does not transport anions when expressed alone in a cellular expression system, that SAO band 3 does not bind stilbenedisulfonates, and that about 50% of the band 3 exists as wild-type/SAO heterodimers. In this report, we show that the kinetics of H2DIDS (4,4'-diisothiocyanatodihydro-2,2'-stilbenedisulfonate) release from the wild-type band 3 in SAO membranes is biphasic. The two phases were present in about equal proportions, with rate constants differing by about 5-fold. In contrast, control cells showed monophasic, exponential kinetics with a rate constant comparable to that of the fast phase of SAO membranes. We assign the fast phase in SAO membranes to H2DIDS release from wild-type subunits within homodirects and the slow phase to H2DIDS release from the wild-type subunit within the heterodimer. No differences were observed in kinetic studies of H2DIDS binding. These results suggest that the mutant band 3 subunit alters the conformation of its neighboring wild- type subunit within the heterodimer, resulting in about a 4-fold higher H2DIDS affinity. Additional evidence suggesting that the interactions in the heterodimer may be confined to a region of the wild-type subunit containing the C-terminal subdomain is presented. The relationship of these subunit interactions to the observation of a reduced cellular anion transport function is discussed.

UR - http://www.scopus.com/inward/record.url?scp=0030067347&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030067347&partnerID=8YFLogxK

U2 - 10.1021/bi952411b

DO - 10.1021/bi952411b

M3 - Article

VL - 35

SP - 251

EP - 257

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 1

ER -