To elucidate the role of phospholipase C beta (PLC beta) isozymes in the ce
rebellum, the distributions of PLC beta 3 and PLC beta 4 were examined in w
ild-type and PLC beta 4-deficient mutant mice using immunohistochemistry, a
nd the functions were evaluated by measurement of type 1 metabotropic gluta
mate receptor (mGluR1)-mediated inward current and Ca2+ mobilization, In wi
ld-type mice, PLC beta 4 was distributed equally in both rostral and caudal
cerebellum, while PLC beta 3 was enriched in the caudal versus the rostral
cerebellum. In PLC beta 4-deficient mice, there was no measurable inward c
urrent or intracellular Ca2+ elevation in the rostral cerebellum, whereas s
mall responses were observed in the caudal cerebellum. In wild-type mice, t
he inward current was observed only following the release of caged GTP gamm
a S, not caged IP3. These results suggest that the signal transduction mach
inery, including receptors, G-proteins, PLC beta 3, PLC beta 4, and effecte
rs, form a functional unit, and the deletion of PLC beta 4 alters this unit
, markedly changing signal transduction efficacy. (C) 1999 Academic Press.