proteins which share similarity to calmodulin. The protein encoded by this gene regulates the gating of voltage-gated calcium ion channels. This protein causes rapid inactivation that is independent of calcium, and does not support Calcium-dependent facilitation. CAbp1 suppresses the inactivated calcium dependent CACNA1D. it also inhibits TRPC5. CABP1 prevents NMDA receptor- induced cellular degeneration. This protein also regulates calcium-dependent activity of inositol 1,4,5-triphosphate receptors, P/Q-type voltage-gated calcium channels, and transient receptor potential channel TRPC5. This gene is predominantly expressed in retina and brain. CaBP1 And CaM both bind to IQ-domain in the cytoplasmic C-terminal domain. Mutations of the IQ-Domain that weakens this two protein binding, stops the functional effect of CaM but not CaBP1. If the N-terminal domain is deleted it abolishes the effect of CaBP1 prolonging Cav1.2 Ca2+ currents, but spared Ca2+-dependent is inactivated due to CaM overexpressed L-CaBP1 suppresses the rise in [Ca2+] in response to physiological agonists acting on purinergic receptors and thus this inhibition occurs in large part to blockade of release from intracellular Ca2+ stores. The related protein neuronal calcium sensor-1did not get affected on the [Ca2+] responses to agonist stimulation. Measurement of [Ca2+] within the ER of permeabilized PC12 cells demonstrated that LCaBP1 directly inhibited InsP3-mediated Ca2+ release. Expression of L-CaBP1 also help in the inhibition of histamine-induced [Ca2+] oscillations in HeLa cells. L-CaBP1 is able to specifically regulate InsP3 receptor-mediated alterations in [Ca2+] during agonist stimulation. Cellular expression of caldendrin is restricted to the somatodendritic compartment, with the exception of hypothalamus, where axonal labeling was detected. CAbP1 and CAbP2 contain a consensus sequence for N-terminal myristoylation. Transcription factor binding sites identified by Qiagen in the CABP1 gene promoter include Nkx2-5, RSRFC4, TAL1, and HSF1. CaBP1 interacts with inositol 1,4,5-triphosphate (InsP3) receptors to elicit channel activation when InsP3 is absent. Clinical significance In schizophrenia, one study demonstrated a decrease in the number of CABP1-expressing cells, specifically in the left dorsolateral prefrontal cortex. This change, however, was compensated on a whole-brain scale by an increase in the protein levels. References EF-hand-containing proteins