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#ATP-powered pumps

3 public questions tagged with this topic.

Membrane Transportation

Which of the following ATP-powered pumps does not hydrolyze ATP during transport?

Pump classification by energy coupling highlights mechanistic differences. P-type ATPases such as Na+/K+ ATPase, SERCA, PMCA hydrolyze ATP phosphorylating conserved aspartate generating E1P E2P intermediates, actively transporting ions against gradients. V-type ATPases acidifying endosomes lysosomes vacuoles comprise Vo proton pore and V1 ATPase rotary motor hydrolyzing ATP to rotate c-ring driving proton translocation without phosphoprotein. ABC transporters dimerize nucleotide binding domains upon ATP binding to expel substrates. F-type ATPases known also as ATP synthases reside in mitochond

Ref: Nelson and Cox, Lehninger, F-Type ATPase Does Not Hydrolyze ATP During ATP Synthesis Mode.

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Membrane Transportation

Which of the following is a characteristic of P-class ATPases?

ATP-driven pumps belong to several mechanistically distinct families distinguished by architecture, subunit composition and mechanism of coupling hydrolysis to transport. P-type family named because first discovered intermediate was phosphorylated enzyme, now understood to include Na+/K+ ATPase maintaining sodium potassium gradients, sarcoplasmic reticulum Ca2+ ATPase SERCA sequestering calcium, plasma membrane Ca2+ ATPase PMCA extruding calcium, gastric H+/K+ ATPase acidifying stomach and heavy metal copper and manganese pumps ATP7A ATP7B. Core mechanism involves conserved aspartate within DK

Ref: Palmgren and Nissen, P-Type ATPases Annual Review Biophys, Mechanism: Phosphorylated Intermediate Formation.

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Membrane Transportation

Which of the following ATP-powered pumps is responsible for maintaining resting membrane potential?

Resting membrane potential stability essential for excitability maintained by differential permeability and active ion distribution. Key player is Na+/K+ ATPase, P-type ion pump encoded by ATP1A genes for alpha isoforms, ATP1B for beta, FXYD for gamma regulatory. Catalytic alpha subunit roughly 112 kDa with ten membrane spans contains nucleotide N domain binding ATP, phosphorylation P domain with conserved DKTGTLT aspartate that forms phosphoenzyme intermediate, actuator A domain and transmembrane ion binding pocket coordinating ions with carbonyl oxygens. Cycle Post-Albers: E1 high Na affinit

Ref: Skou and Glynn, P-Type ATPases Review, Na+/K+ ATPase Role in Resting Membrane Potential Maintenance.

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