Let A ⊆ B be a ring extension and G be a set of Asubmodules of B. We introduce a class of closure operations on G (which we call multiplicative operations on (A, B, G)) that generalizes the classes of star, semistar and semiprime operations. We study how the set Mult(A, B, G) of these closure operations vary when A, B or G vary, and how Mult(A, B, G) behave under ring homomorphisms. As an application, we show how to reduce the study of star operations on analytically unramified one-dimensional Noetherian domains to the study of closures on finite extensions of Artinian rings.