Retinal isomerase catalyses the conversion of? – Physiology MCQ

Retinal isomerase catalyses the conversion of?
A. 11-cis retinal to rhodopsin
B. All trans retinal to 11-cis retinal
C. Lumirhodopsin to metarhodopsin
C. Bathorhodopsin to lumirhodopsin

Correct answer : B. All trans retinal to 11-cis retinal

• When light energy is absorbed by rhodopsin, photoactivation of electrons in the retinal portion of rhodopsin leads to the change of cis form of retinal into the all trans form.
• The first stage in the reformation of rhodopsin is to reconvert the all trans retinal into 11 cis retinal.
• This process is catalysed by the enzyme – retinal isomerase.

Ref: Textbook of Medical Physiology, Guyton and Hall, 11th edition, page 629.