Question

1. Which transporter is responsible for acidifying the lumen of lysosomes?

   		F-type ATPase
   		ABC transporter
   		V-type ATPase
   		P-type pump

Answer 1

Among the given options, V Type ATPase is the best match for transporter responsible for acidifying lumen of Lysosomes.

Lysosomes are cell organelles that breakdown complex macromolecules into absorbable nutrients that can be utilized by the cells. This process involves hydrolytic enzymes that require acidic pH for their activation. This acidic pH is generated and maintained by a special type of ATPase called as V-Type ATPase found in lysosomal lumen that utilizes metabolic energy in the form of ATP and pumps proton across the lysosomal lumen creating a gradient across the organelle. Defects in these enzymes can lead to Human diseases such as Osteopetrosis, distal renal tubular acidosis and a rare disease called X-linked myopathy with excessive autophagy.

the other transporters mentioned,

F type ATPase is present in in mitochondrial membrane, also known as Complex V, and is involved in Oxidative Phosphorylation

ABC transporter is present in various extra and intra cellular membranes and are involved in translocation of substrates such as sugars, amino acids, metal ions, peptides, and proteins etc.

P type pump is present in mucosal lining of stomach and is involved in acidification of gastric contents.