Parvalbumin in Cat Brain: Isolation, Characterization, and Localization

Abstract

Because of the increasing evidence that Ca2+-binding proteins have important regulating functions in nerve cells and because of the indications that there are species differences in the structures of these proteins, parvalbumin was purified from cat brain and muscle. Brain and muscle parvalbumins were found to be indistinguishable from each other in their biochemical and immunological properties. However, cat parvalbumin differs from all other mammalian parvalbumins by its apparently lower Mr on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 10-11K (compared to rat parvalbumin, 12K), and a lower pI of 4.6 (rat parvalbumn, 4.9), in the tryptic peptide maps, and in the immunological properties, indicating a distinct primary structure. With the purified parvalbumin as antigen, polyclonal antibodies were raised in rabbits and these were subsequently used for immunohistochemical localizations of parvalbumin in the cat brain. In the visual cortices of adult cats immunoreactive neurons were present throughout layers II and IV. In cerebellar cortex, Purkinje basket, and stellate cells were immunoreactive. Comparison with staining patterns obtained with antiserum against rat parvalbumin revealed some cross-reactivity but confirmed the existence of species differences in the antigenic structure of rat and cat parvalbumin.