Kinetics of passive anion transport across the human erythrocyte membrane

Oligomeric structure and the anion transport function of human erythrocyte band 3 protein

“…The halides [22], HCO3 [151], phosphate [24,52], sulfate [127], borohydride [58], superoxide [82], lithium carbonate [43] and dithionite [124] are all transported, though at widely varying rates. For example, C1/CI exchange at pH 7 is about 10,000 times faster than SO4/SO 4 exchange; as the pH is reduced below 7, chloride transport is inhibited and sulfate transport is accelerated [73].…”

“…2 l, 48,73,[122][123][124], and it is generally agreed that the kinetics imply that there must be at least two anion binding sites per functional unit of transport. The first is a substrate site, and the second is a site that is responsible for self-inhibition of anion transport at high substrate concentrations [21].…”

“…These topics are prefaced by a brief general review of human band 3 structure and function. The reader is referred elsewhere for detailed discussion of band 3 anion exchange kinetics [12,21,38,39,48,59,73,93,[122][123][124]127], electrical properties [40,74], conformational changes associated with transport [12,59,73,86,108], the structure and disposition of the polypeptide chain [ll, 29,60,68,73,85,90,112,119,139,144,155],…”

A novel rapid‐reaction spectrophotometric method for monitoring monovalent anion exchange by human erythrocyte band 3

“…measuring monovalent anion exchange using radiotracer methods (2) at low temperatures ( 0 -4 ~ C ). In recent years, various rapid-reaction spectroscopic (3)(4)(5)(6), or fluorometric (7)(8)(9) methods have been developed to continuously monitor band 3 -mediated anion exchange.…”

“…However, the spectroscopic method was limited to the use of a divalent anion ( 3 ), while the fluorometric method monitored chloride transport, but only in hemoglobin-free resealed ghosts, because of technical limitations ( 7 ). In order to study the transport of small monovalent anions using intact erythrocytes, I have developed, and report here, a new approach where the color change associated with the reaction of intracellular methemoglobin with thiocyanate (SCN-) ( 10 ) was used to monitor the appearance of SCN-within intact human erythrocytes as well as resealed ghosts.…”