Format

Send to

Choose Destination
Nat Neurosci. 2004 Oct;7(10):1079-87. Epub 2004 Sep 26.

Essential role of Ca2+-binding protein 4, a Cav1.4 channel regulator, in photoreceptor synaptic function.

Author information

1
Department of Ophthalmology, University of Washington, Box 356485, Seattle, Washington 98195, USA. fanfan@u.washington.edu <fanfan@u.washington.edu>

Abstract

CaBP1-8 are neuronal Ca(2+)-binding proteins with similarity to calmodulin (CaM). Here we show that CaBP4 is specifically expressed in photoreceptors, where it is localized to synaptic terminals. The outer plexiform layer, which contains the photoreceptor synapses with secondary neurons, was thinner in the Cabp4(-/-) mice than in control mice. Cabp4(-/-) retinas also had ectopic synapses originating from rod bipolar and horizontal cells tha HJt extended into the outer nuclear layer. Responses of Cabp4(-/-) rod bipolars were reduced in sensitivity about 100-fold. Electroretinograms (ERGs) indicated a reduction in cone and rod synaptic function. The phenotype of Cabp4(-/-) mice shares similarities with that of incomplete congenital stationary night blindness (CSNB2) patients. CaBP4 directly associated with the C-terminal domain of the Ca(v)1.4 alpha(1)-subunit and shifted the activation of Ca(v)1.4 to hyperpolarized voltages in transfected cells. These observations indicate that CaBP4 is important for normal synaptic function, probably through regulation of Ca(2+) influx and neurotransmitter release in photoreceptor synaptic terminals.

PMID:
15452577
PMCID:
PMC1352161
DOI:
10.1038/nn1320
[Indexed for MEDLINE]
Free PMC Article

Publication types, MeSH terms, Substances, Secondary source IDs, Grant support

Publication types

MeSH terms

Substances

Secondary source IDs

Grant support

Supplemental Content

Full text links

Icon for Nature Publishing Group Icon for PubMed Central
Loading ...
Support Center