Calnexin (Cnx) has been characterized as a
membrane-bound protein that transiently interacts in a
unique chaperone system with newly synthesized
glycoproteins in order to allow the establishment of their
proper tertiary and, in most cases, quarternary structures.
The aim of the study was to identify and to locate the
expression of Cnx in the three major salivary glands of
humans by different methods. Strong expression of Cnx
protein and mRNA were generally found in serous
salivary secretory units. With regard to mucous secretory
units, expression of Cnx was only detectable at a low
level in mucous acinar cells of sublingual glands, but not
of submandibular glands. Expression of Cnx was always
preserved in the surface epithelium of intralobar and
interlobular duct segments. In addition, expression of
Cnx was detected in sebaceous glands of parotid tissues,
with a distribution pattern resembling that seen in
sebaceous glands of the normal skin. In conclusion,
production of saliva is associated with the expression of
Cnx. Synthesis of molecules in mucous secretory units is
not necessarily associated with a strong Cnx expression,
whereas synthesis in serous secretory units apparently is.
The tissue-specific Cnx expression is also paralleled by
the observation that the secretions produced by the major
salivary glands differ in their composition and amoun
