I never thought about this, but why is insulin considered a hormone vs. an enzyme? If not an enzyme, then is it a grave misconception that insulin breaks down sugar? Then, what does insulin do, exactly?
And, for extra credit: If hormones are produced/stored in glands, where are enzymes produced? Stored?
Guess I’ve harbored some mixed-up conceptions about this…
Insulin does not catalyze any reaction, so it’s not an enzyme. As a messenger, it regulates (indirectly) the activities of proteins that do catalyze reactions (enzymes).
Enzymes are produced in just about every cell.
A polypeptide hormone secreted by the islets of Langerhans and functioning in the regulation of the metabolism of carbohydrates and fats, especially the conversion of glucose to glycogen, which lowers the blood glucose level.
Insulin is an honest-to-goodness card-carrying hormone. Don’t let the sloppy language of others confuse you.
I suspect that the misconceptions about insulin stem from the many glib and patronizing explanations regarding its function(s).
Interestingly, insulin not only stimulates the enzymes which help to store sugar, build up fat, etc., but it also inhibits other enzymes which tend to release sugar from storage, breakdown fat, etc. Very clever.
Also clever is insulin’s ability to directly turn off and reduce the levels of other hormones that would have opposed insulin. Those with some knowledge of endocrine physiology will recall, for example, that insulin inhibits the production and release of glucagon (with glucagon being an anti-insulin hormone).