Calcium-binding protein 1

Calcium binding protein 1 is a protein that in humans is encoded by the CABP1 gene.[3] Calcium-binding protein 1 is a calcium-binding protein[4] discovered in 1999.[5] It has two EF hand motifs and is expressed in neuronal cells in such areas as hippocampus, habenular nucleus of the epithalamus, Purkinje cell layer of the cerebellum, and the amacrine cells and cone bipolar cells of the retina.

CABP1
Available structures PDB Human UniProt search: PDBe RCSB List of PDB id codes 2K7B, 2K7C, 2K7D, 2LAN, 2LAP, 3OX5, 3OX6
Identifiers
Aliases	CABP1, CALBRAIN, HCALB_BR, calcium binding protein 1
External IDs	OMIM: 605563 HomoloGene: 128292 GeneCards: CABP1
Gene location (Human) Chr. Chromosome 12 (human)[1] Band 12q24.31 Start 120,640,552 bp[1] End 120,667,324 bp[1]
Gene ontology Molecular function • GO:0048551 enzyme inhibitor activity • calcium ion binding • GO:0001948 protein binding • nuclear localization sequence binding • calcium-dependent protein binding • metal ion binding Cellular component • cytoplasm • perinuclear region of cytoplasm • cell junction • Golgi membrane • cell membrane • postsynaptic membrane • Golgi apparatus • cell cortex • synapse • cytoskeleton • GO:0097483, GO:0097481 postsynaptic density • membrane • extracellular Biological process • negative regulation of protein import into nucleus • GO:0048553 negative regulation of catalytic activity • visual perception • response to stimulus Sources:Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	9478	n/a
Ensembl	ENSG00000157782	n/a
UniProt	Q9NZU7	n/a
RefSeq (mRNA)	NM_031205 NM_001033677 NM_004276	n/a
RefSeq (protein)	NP_001028849 NP_004267 NP_112482	n/a
Location (UCSC)	Chr 12: 120.64 – 120.67 Mb	n/a
PubMed search	[2]	n/a
Wikidata
View/Edit Human

Calcium-binding protein 1 which is a neuron -specific member of the calmodulin (CaM) superfamily which modulates Ca²⁺-dependent activity of inositol trisphosphate receptors (InsP3RS).[6] L-CaBP1 is also associated with the cytoskeleton structures. But the S-CaBP1 is situated in or near the plasma membrane. In brain, CaBp1 is found in the cerebral cortex and hippocampus and in the protein, Cabp1 is found in cone bipolar and amacrine cells. We can also express that CaBP1 may regulate Ca²⁺ dependent activity of InSP3Rs by promoting structural contacts between suppressor and core domains but has no effect on INsP3 binding to the receptor. CaBP1 contains four EF-hands in two separate domains namely, EF1 and Ef2 is contained in N-domain whereas Ef3 and EF4 is contained in c domain to which Ca²⁺ binds.[7] Calcium-binding protein 1 (CaBP1) is placed in the lumen of the endoplasmic reticulum.it is relocated outside cells during apoptosis and involved in the phagocytosis of apoptotic cells.[8] CaBP1[7] and CaM.[9][10] lobes fold independently. CaBP1-CaM chimeras based on exchange of three elements these are N-lobe, C-lobe and inter lobe linker. Expression of CaBP1 helps to block Ca²⁺-dependent facilitation of P/Q-type Ca²⁺ current which is markedly reduced facilitation of synaptic transmission.

Protein structure

Protein that attributes for CABP1 Gene is homodimer. It interacts with ITPR1, ITPR2 and ITPR3 via C-terminus. The binding is calcium dependent and the interaction correlates with calcium concentration. CABP1 also interacts with CACNA1A in the pre and post synaptic membranes via C-terminal calcium binding motif. It also interacts with CACNA1C via C-terminal C and IQ motifs. It interacts with TRPC5 and also interacts with MAP1LC3B via C-terminus and EF-hands 1 and 2 respectively. It interacts with C9orf9. It also interacts NSMF via the central NLF- containing motif region. This interaction occurs in calcium dependent manner after the Synaptic NMDA receptor stimulation and thus this prevents nuclear import of NSMF.[11]

Function

Calcium binding proteins are an important component of calcium mediated cellular signal transduction. This gene encodes a protein that belongs to a subfamily of calcium binding 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.[12] 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.[3]

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 Ca_v1.2 Ca²⁺ currents, but spared Ca²⁺-dependent is inactivated due to CaM[13] 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.[14] 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.[15]

References

1. GRCh38: Ensembl release 89: ENSG00000157782 - Ensembl, May 2017
2. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
3. "Entrez Gene: Calcium binding protein 1".
4. McCue HV, Haynes LP, Burgoyne RD (August 2010). "The diversity of calcium sensor proteins in the regulation of neuronal function". Cold Spring Harbor Perspectives in Biology. 2 (8): a004085. doi:10.1101/cshperspect.a004085. PMC 2908765. PMID 20668007.
5. Yamaguchi K, Yamaguchi F, Miyamoto O, Sugimoto K, Konishi R, Hatase O, Tokuda M (February 1999). "Calbrain, a novel two EF-hand calcium-binding protein that suppresses Ca²⁺/calmodulin-dependent protein kinase II activity in the brain". The Journal of Biological Chemistry. 274 (6): 3610–6. doi:10.1074/jbc.274.6.3610. PMID 9920909.
6. Haeseleer F, Sokal I, Verlinde CL, Erdjument-Bromage H, Tempst P, Pronin AN, Benovic JL, Fariss RN, Palczewski K (2000). "Five members of a novel Ca²⁺-binding protein (CABP) subfamily with similarity to calmodulin". The Journal of Biological Chemistry. 275 (2): 1247–60. doi:10.1074/jbc.275.2.1247. PMC 1364469. PMID 10625670.
7. Li C, Chan J, Haeseleer F, Mikoshiba K, Palczewski K, Ikura M, Ames JB (January 2009). "Structural insights into Ca²⁺-dependent regulation of inositol 1,4,5-trisphosphate receptors by CaBP1". The Journal of Biological Chemistry. 284 (4): 2472–81. doi:10.1074/jbc.M806513200. PMC 2629100. PMID 19008222.
8. "Gene Dmel\CaBP1". FlyBase.
9. Masino L, Martin SR, Bayley PM (2000). "Ligand binding and thermodynamic stability of a multidomain protein, calmodulin". Protein Science. 9 (8): 1519–29. doi:10.1110/ps.9.8.1519. PMC 2144730. PMID 10975573.
10. Tsalkova TN, Privalov PL (1985). "Thermodynamic study of domain organization in troponin C and calmodulin". Journal of Molecular Biology. 181 (4): 533–44. doi:10.1016/0022-2836(85)90425-5. PMID 3999139.
11. "CABP1 Gene". GeneCards.
12. Lee A, Westenbroek RE, Haeseleer F, Palczewski K, Scheuer T, Catterall WA (2002). "Differential modulation of Ca(v)2.1 channels by calmodulin and Ca2+-binding protein 1". Nature Neuroscience. 5 (3): 210–7. doi:10.1038/nn805. PMC 1435861. PMID 11865310.
13. Zhou H, Yu K, McCoy KL, Lee A (August 2005). "Molecular mechanism for divergent regulation of Cav1.2 Ca²⁺ channels by calmodulin and Ca²⁺-binding protein-1". The Journal of Biological Chemistry. 280 (33): 29612–9. doi:10.1074/jbc.M504167200. PMID 15980432.
14. Bernstein HG, Seidenbecher CI, Smalla KH, Gundelfinger ED, Bogerts B, Kreutz MR (August 2003). "Distribution and cellular localization of caldendrin immunoreactivity in adult human forebrain". The Journal of Histochemistry and Cytochemistry. 51 (8): 1109–12. doi:10.1177/002215540305100816. PMID 12871994.
15. Bernstein HG, Sahin J, Smalla KH, Gundelfinger ED, Bogerts B, Kreutz MR (November 2007). "A reduced number of cortical neurons show increased Caldendrin protein levels in chronic schizophrenia". Schizophrenia Research. 96 (1–3): 246–56. doi:10.1016/j.schres.2007.05.038. PMID 17719205.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.