The role of calbindin D-28k in cerebellum

Calbindin-D28k (calbindin) is a calcium-binding protein expressed in many neuronal populations of the central nervous system. It is generally thought of as calcium buffer, but its cell type-specific physiological roles are unknown. We show that cerebellar Purkinje cell-specific calbindin null mutant mice exhibit a distinct alteration in motor coordination which is primarily due to impaired processing of sensory information. This occurs independent of alterations of synaptic long-term depression but concomitant with selective alteration of  synaptically-evoked Ca2+ transients. Whereas AMPA-receptor-mediated transients in Purkinje cell spines and dendrites have larger amplitudes and decay faster, the delayed mGluR-mediated synaptic Ca2+ signal is unaffected. We conclude that calbindin within Purkinje cells, possibly through direct modulation of dendritic Ca2+, is a critical molecular constituent of sensorimotor integration.