P22947 (TXCAS_DENPO) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Calciseptin Alternative name(s): Calciseptine Short name=CaS L-type calcium channel blocker
Organism	Dendroaspis polylepis polylepis (Black mamba)
Taxonomic identifier	8620 [NCBI]
Taxonomic lineage	cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Sauropsida › Sauria › Lepidosauria › Squamata › Scleroglossa › Serpentes › Colubroidea › Elapidae › Elapinae › Dendroaspis › Dendroaspis polylepis

Protein attributes

Sequence length	60 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	This specific blocker of the L-type calcium channel (Cav1/CACNA1) is a smooth muscle relaxant and an inhibitor of cardiac contractions. Ref.3
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Miscellaneous	The sensitivity is higher in cells of the cardiovascular system. Neuronal, and insulinoma cells L-type calcium channel are more resistant. A total resistance is found in skeletal muscle cells.
Sequence similarities	Belongs to the snake three-finger toxin family. L-type calcium blocker subfamily.

Ontologies

Keywords
Cellular component	Secreted
Molecular function	Calcium channel inhibitor Cardiotoxin Ion channel impairing toxin Neurotoxin Toxin
PTM	Disulfide bond
Technical term	Direct protein sequencing
Gene Ontology (GO)
Biological_process	modification of morphology or physiology of other organism Inferred from electronic annotation. Source: InterPro
Cellular_component	extracellular region Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular_function	calcium channel inhibitor activity Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Chain	1 – 60	60	Calciseptin		PRO_0000093667
Amino acid modifications
	Disulfide bond	3 ↔ 22		By similarity
	Disulfide bond	17 ↔ 39		By similarity
	Disulfide bond	41 ↔ 52		By similarity
	Disulfide bond	53 ↔ 58		By similarity

Sequences

	Sequence		Length	Mass (Da)
	P22947 [UniParc]. Last modified August 1, 1991. Version 1. Checksum: 2F14B05972A40FFF	FASTA	60	7,044
	10 20 30 40 50 60 RICYIHKASL PRATKTCVEN TCYKMFIRTQ REYISERGCG CPTAMWPYQT ECCKGDRCNK

References

[1]	"Calciseptine, a peptide isolated from black mamba venom, is a specific blocker of the L-type calcium channel." de Weille J.R., Schweitz H., Maes P., Tartar A., Lazdunski M. Proc. Natl. Acad. Sci. U.S.A. 88:2437-2440(1991) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE. Tissue: Venom.
[2]	"Solution synthesis of calciseptine, an L-type specific calcium channel blocker." Kuroda H., Chen Y.-N., Watanabe T.X., Kimura T., Sakakibara S. Pept. Res. 5:265-268(1992) [PubMed] [Europe PMC] [Abstract] Cited for: SYNTHESIS.
[3]	"Flanking proline residues identify the L-type Ca2+ channel binding site of calciseptine and FS2." Kini R.M., Caldwell R.A., Wu Q.Y., Baumgarten C.M., Feher J.J., Evans H.J. Biochemistry 37:9058-9063(1998) [PubMed] [Europe PMC] [Abstract] Cited for: FUNCTION, SYNTHESIS OF 41-48.

Cross-references

Sequence databases
PIR	A39165.
3D structure databases
ProteinModelPortal	P22947.
SMR	P22947. Positions 1-60.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Phylogenomic databases
HOVERGEN	HBG006553.
Family and domain databases
InterPro	IPR003571. Snake_toxin. IPR018354. Snake_toxin_BS. [Graphical view]
Pfam	PF00087. Toxin_1. 1 hit. [Graphical view]
PROSITE	PS00272. SNAKE_TOXIN. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

TXCAS_DENPO

Accession

Primary (citable) accession number: P22947

Entry history

Integrated into UniProtKB/Swiss-Prot:	August 1, 1991
Last sequence update:	August 1, 1991
Last modified:	April 3, 2013
This is version 61 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Animal Toxin Annotation Program

Annotation program

Chordata Protein Annotation Program