Question

Despite combining first transferring materials with differenct receptors and activating the same secondary transferring material, why is the result appear to be opposite (contrract or opposite)?

Answer 1

RECEPTORS are nothing but CARRIER  PROTEINS in the cell membrane.they are maximum protein in nature .

CARRIER PROTEIN transfers the material (you can also called SOLUTE) across the lipid membrane or cell membrane with respect to concentration gradient.

CARRIER PROTEIN -SOLUTE TRANSFER MECHANISM IS SIMILAR TO ENZYME-SUBSTRATE REACTION.

IFyou want to understand the above question ,you must know regarding ONE concept...

1.V MAX...MAXIMUM VELOCITY OF AN ENZYME

1.V MAX------IF THE CONCENTRATION OF SUBSTRATE IS INCREASED ,MORE AND MORE THE ACTIVITY OF ENZYME INCREASES UNTIL ALL ACTIVE SITES ARE FULFILLED (VMAX. ). BEYOND THIS THERE IS NO INCREASE IN THE REACTION..THE REACTION IS STABLE AND DECREASES GRADUALLY.

WHEN SUBSTRATE LEVELS INCREASES BEYOND THE LIMIT THE ENZYMES DOES NOT RESPOND .. IN THE SAME WAY WHEN TRANSFERRING MATERIAL CONCENTRATION REACHES MAXIMUM THEN ALL THE CARRIER PROTEINS(RECEPTORS) ARE SATURATED, SO THAT THERE IS NO SITE IS AVAILABLE FOR TRANSFERRING MATERIAL TO BOUND WITH CARRIER PROTEIN OR RECEPTOR... SO THERE IS NO TRANSFERING OF MATERIAL ACROSS THE MEMBRANE SECOND TIME BECAUSE OF SATURATION OF RECEPTORS BY TRANSFERRING MATERIAL IN THEIR ACTIVE SITES. BECAUSE OF  THIS THE RESULT WILL APPEAR TO BE OPPOSITE.