It has long been known that the salivary glands of hematophagous (blood-feeding) arthropods secrete soluble apyrases, which are potent nucleotide hydrolyzing enzymes capable of hydrolyzing extracellular ATP and ADP, the latter being a major agonist contributing to platelet aggregation. Only recently, however, has the identification of proteins homologous to these apyrases been reported in non-blood-feeding organisms such as rodents and humans.
is the homologue of soluble apyrases found in blood-sucking insects. This family of nucleotidases is unrelated in sequence to more well-studied nucleotidases, and very little is known about the enzymatic mechanism. By multiple sequence alignment, eight regions that are highly conserved in the hSCAN-1 family were identified and named.