Na+-K+ ATPase is a-
Correct Answer: Transmembrane protein
Description: Ans. is 'c' i.e., Transmembrane protein * Ion pumps (including Na+ - K+ ATPase) and channels are intergral (Transmembrane) proteins.* Most of the membrane proteins are glycoproteins. There are following types of membrane proteins1) Integral (Transmembrane or intrinsic) Proteins : -# These proteins pass 'through and through', i.e., they run (span) the entire length of lipid bilayer. Integral proteins are globular and amphipathic, consisting of two hydrophilic ends separated by an intervening hydrophobic region that traverses the hydrophobic core of the bilayer. Integral proteins interact by non-polar (hydrophobic) interacts with the fatty acyl groups of phospholipids in the cell membrane and require the use of detergents for their solubilization. Integral proteins are asymmetrically distributed across the membrane bilayer.2) Peripheral (Extrinsic) proteins# Peripheral proteins are present on the surface of the membrane and do not penetrate all the way through. They are located on both surface of membrane, outer and inner. Peripheral proteins do not interact directly with the phospholipid in the bilayer. They bound to the hydrophilic regions of the transmembrane proteins through electrostatic and hydrogen bonds. However, some (not all) proteins bind to membrane via a covalentently attached lipid anchor, i.e., interaction with polar (hydrophilic) lipid head groups in the membrane.# As they do not interact directly with hydrophobic core of phospholipids, they do not require use of detergents for their release. They can be released by treatment with salt solutions of high ionic strength.# Peripheral proteins serve as cell adhesion molecules (CAMs) that anchor cells to neighboring cells and to basal lamina. They also contribute to cytoskeleton when present on the inside of the membrane, e.g., spectrin, ankyrin, band 4.1 in RBCs.Important functions of cell membrane proteinsIntegral (transmembrane) proteinsPeripheral (extrinsic) proteins* Channels (pores)* Receptors* Enzymes* Carrier proteins* Ion pumps* Adhesion molecules* Enzymes* Controller of transport of substance
Category:
Physiology
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