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#RBC membrane protein

2 public questions tagged with this topic.

Plasma Membrane Proteins

Which RBC membrane protein is essential for Cl⁻ transport?

Physiology of carbon dioxide delivery relies on chloride bicarbonate exchange across erythrocyte membrane rather than G protein signaling. Authentic transporter Band 3 anion exchanger 1 SLC4A1 abundant integral protein fourteen transmembrane helices catalyzing electroneutral one to one antiport of chloride for bicarbonate at high turnover supporting conversion of CO2 to bicarbonate via carbonic anhydrase for plasma carriage known as chloride shift Hamburger phenomenon. At pulmonary capillaries exchange reverses enabling CO2 exhalation. GPCR family members are seven-transmembrane receptors coupling to heterotrimeric G proteins generating second messengers cAMP inositol trisphosphate diacylglycerol activating kinases but not transporting chloride as primary mode. Glycophorin major single-pass sialoglycoprotein provides glycocalyx negative charge and pathogen receptor lacking transport activity, spectrin filamentous tetrameric cytoskeletal protein maintains biconcave elasticity lacking ion translocation. Therefore scientifically validated chloride transporter is Band 3 although answer choice listed as GPCR in this dataset reflects probable curation inconsistency noted here, emphasizing need to recognize Band 3 as genuine chloride shift mediator for acid base and gas transport physiology.

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 15, AE1 Band 3 Chloride-Bicarbonate Exchanger.

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Plasma Membrane Proteins

Which of the following is a structural protein providing support to the RBC membrane?

Erythrocyte membrane mechanical resilience originates from spectrin ankyrin network linkage. Ankyrin-1 large adaptor of approximately two hundred six kilodaltons comprises three domains: N-terminal membrane binding domain of twenty four ankyrin repeats each thirty three residues forming elongated solenoid that binds high affinity site on Band 3 cytoplasmic domain residues one seventy five to one eighty five and other integral proteins sodium-potassium ATPase, sodium channel Nav1.5, cell adhesion molecule L1; central spectrin binding domain of about one hundred residues binding beta spectrin repeat fourteen to fifteen; C-terminal regulatory domain including death domain modulating affinity. Ankyrin bridges Band 3 to beta spectrin tetramer about two hundred nanometers comprising antiparallel alpha beta heterodimers assembling head to head. Protein 4.1R complex links glycophorin C to junctional actin spectrin nodes. Quantitative deficiency reduces spectrin incorporation about fifty percent leading to hereditary spherocytosis spherocytic rigid cells hemolysis splenomegaly. Thus ankyrin provides vertical coupling essential for biconcave disc stability during circulation through narrow capillaries and prevents vesiculation under shear stress.

Ref: Bennett and Healy, Membrane Protein Complexes and Ankyrin Function, Annu Rev Cell Dev Biol.

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