Fascinating families of proteins: electrophoresis of human saliva.

I 33 SDS/PAGE has been used to study the proIntroduction The proteins in saliva are synthesized mainly in the acinar cells of the major salivary glands, namely the parotid, submandibular and sublingual. Minor components derived from serum are also present in the secretions of these three pairs of glands which, together with the secretions of the minor glands, gingival exudate, micro-organisms and exfoliated buccal epithelial cells, constitute whole or mixed saliva, sometimes known as oral fluid. The proteins present in human salivary duct secretions are shown in Table 1. The major ones are proline-rich proteins, histatins (histidine-rich proteins), a-amylase and mucins. The first three occur as polymorphic families of proteins with proline-rich proteins comprising about two thirds of the total protein in duct secretion [ 11. Contemporary electrophoretic techniques have facilitated extensive studies on these families of proteins and have yielded fascinating new information about them.