Journal of Neuroscience, Vol 6, 954-961, Copyright © 1986 by Society for Neuroscience
PCPP-260, a Purkinje cell-specific cyclic AMP-regulated membrane phosphoprotein of Mr 260,000
SI Walaas, AC Nairn and P Greengard
The present study reports the existence of Purkinje cell-specific
phosphoprotein, Mr 260,000 (PCPP-260), a neuronal membrane phosphoprotein,
in cerebellar Purkinje cells. PCPP-260, which on sodium dodecyl
sulfate-polyacrylamide gel electrophoresis has an apparent molecular mass
of 260,000 Da, has been found to be phosphorylated in particulate
preparations by endogenous or added exogenous cyclic AMP- dependent protein
kinase, but not by cyclic GMP-dependent, calcium/calmodulin-dependent or
calcium/phospholipid-dependent protein kinases. The protein has been found
in high concentrations in all mammalian cerebella so far analyzed,
including human cerebellum. One- and two-dimensional electrophoretic and
peptide mapping analyses of proteins in other brain regions show that a
closely related 265,000 Da phosphoprotein also exists, albeit in low
concentrations, outside the cerebellum. Analysis of cerebella from mutant
mice, deficient in either Purkinje cells or in granule cells, indicates
that PCPP-260 within the cerebellum is restricted to Purkinje cells.
Furthermore, subcellular fractionation of rat cerebella indicates that the
protein is an integral membrane protein. The cAMP-regulated phosphorylation
of PCPP- 260 is presumably involved in membrane functions important to
Purkinje cells.
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