Parvalbumin in non-muscle tissues of the rat. Quantitation and immunohistochemical localization

Parvalbumin, a high affinity Ca2+-binding protein, is known to be expressed only in muscles and brain in the rat. We have investigated its distribution and characteristics in other rat tissues by several biochemical and immunohistochemical methods. Evidence for the presence of parvalbumin in teeth, bone, skin, prostate, seminal vesicles, testes, and ovary is given by two-dimensional polyacrylamide gel electrophoresis, immunoblotting ("Western technique") of one-dimensional gels, and its concentration measured by reverse phase high performance liquid chromatography. The distribution within several parvalbumin-positive organs was monitored by the immunohistochemical peroxidase-antiperoxidase method. In teeth, only ameloblasts reacted with anti-rat parvalbumin serum and in bone the calcified extracellular cartilage was the target of the immunoreaction. The panniculus carnosus was the exclusive site of parvalbumin in the skin. Besides the already known parvalbumin distribution in the brain, parvalbumin is also expressed in distinct cell types of the peripheral nervous system. Leydig cells were found to be the only parvalbumin location in testes. These observations lead us to conclude that parvalbumin in contrast to the multifunctional and constitutive calmodulin must function in Ca2+-dependent processes related to specific cell types.