Other contributors have said "Function of pepsinogen in digestive system?" is the same question as "What is the function of Pepsinogens?" If you believe that these are not asking the same thing and should be answered differently, click here
Gastric juice, as known is an acidic juice present in the stomach. Pepsinogen in gastric juice conveys it to convert the pieces of food into a thick paste which then continues on. ^_^
Here is an example for a variable, which is a function (function-pointer, actually): int (*myfun)(const char *s); myfun = puts; myfun ("Hello, world");