ID   CXAB_CONPE              Reviewed;          61 AA.
AC   P50985; Q9BP57;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   16-JAN-2004, sequence version 2.
DT   16-JUN-2009, entry version 64.
DE   RecName: Full=Alpha-conotoxin PnIB;
DE   Flags: Precursor;
OS   Conus pennaceus (Feathered cone).
OC   Eukaryota; Metazoa; Mollusca; Gastropoda; Orthogastropoda;
OC   Apogastropoda; Caenogastropoda; Sorbeoconcha; Hypsogastropoda;
OC   Neogastropoda; Conoidea; Conidae; Conus.
OX   NCBI_TaxID=37335;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   MEDLINE=21105969; PubMed=11158371;
RA   Conticello S.G., Gilad Y., Avidan N., Ben-Asher E., Levy Z.,
RA   Fainzilber M.;
RT   "Mechanisms for evolving hypervariability: the case of conopeptides.";
RL   Mol. Biol. Evol. 18:120-131(2001).
RN   [2]
RP   PROTEIN SEQUENCE OF 45-60.
RC   TISSUE=Venom;
RX   MEDLINE=94347719; PubMed=8068627; DOI=10.1021/bi00198a018;
RA   Fainzilber M., Hasson A., Oren R., Burlingame A.L., Gordon D.,
RA   Spira M.E., Zlotkin E.;
RT   "New mollusc-specific alpha-conotoxins block Aplysia neuronal
RT   acetylcholine receptors.";
RL   Biochemistry 33:9523-9529(1994).
RN   [3]
RP   FUNCTION, SYNTHESIS, AND MUTAGENESIS OF LEU-54 AND SER-55.
RX   PubMed=10545176; DOI=10.1021/bi991252j;
RA   Luo S., Nguyen T.A., Cartier G.E., Olivera B.M., Yoshikami D.,
RA   McIntosh J.M.;
RT   "Single-residue alteration in alpha-conotoxin PnIA switches its nAChR
RT   subtype selectivity.";
RL   Biochemistry 38:14542-14548(1999).
RN   [4]
RP   SULFATION AT TYR-59.
RX   MEDLINE=99242956; PubMed=10226369;
RX   DOI=10.1002/(SICI)1096-9888(199904)34:4<447::AID-JMS801>3.3.CO;2-T;
RA   Wolfender J.L., Chu F., Ball H., Wolfender F., Fainzilber M.,
RA   Baldwin M.A., Burlingame A.L.;
RT   "Identification of tyrosine sulfation in Conus pennaceus conotoxins
RT   alpha-PnIA and alpha-PnIB: further investigation of labile sulfo- and
RT   phosphopeptides by electrospray, matrix-assisted laser
RT   desorption/ionization (MALDI) and atmospheric pressure MALDI mass
RT   spectrometry.";
RL   J. Mass Spectrom. 34:447-454(1999).
RN   [5]
RP   X-RAY CRYSTALLOGRAPHY (1.1 ANGSTROMS) OF 45-60, AND DISULFIDE BONDS.
RX   MEDLINE=97444322; PubMed=9298951; DOI=10.1021/bi9713052;
RA   Hu S.H., Gehrmann J., Alewood P.F., Craik D.J., Martin J.L.;
RT   "Crystal structure at 1.1-A resolution of alpha-conotoxin PnIB:
RT   comparison with alpha-conotoxins PnIA and GI.";
RL   Biochemistry 36:11323-11330(1997).
CC   -!- FUNCTION: Alpha-conotoxins act on postsynaptic membranes, they
CC       bind to the nicotinic acetylcholine receptors (nAChR) and thus
CC       inhibit them. This toxin blocks mammalian nAChRs (alpha-7 > alpha-
CC       3/beta-2).
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom duct.
CC   -!- MISCELLANEOUS: PnIB[L54A] corresponds to PnIA[N11S], whereas
CC       PnIB[S55N] corresponds to PnIA[A10L].
CC   -!- SIMILARITY: Belongs to the conotoxin A superfamily. Alpha-type
CC       family.
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DR   EMBL; AF215088; AAG60509.1; -; mRNA.
DR   PIR; B54877; B54877.
DR   PDB; 1AKG; X-ray; 1.10 A; A=45-60.
DR   PDBsum; 1AKG; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0045211; C:postsynaptic membrane; IEA:UniProtKB-KW.
DR   GO; GO:0030550; F:acetylcholine receptor inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0009405; P:pathogenesis; IEA:UniProtKB-KW.
DR   GO; GO:0007268; P:synaptic transmission; IEA:UniProtKB-KW.
DR   InterPro; IPR009958; Conotoxin_a-typ.
DR   InterPro; IPR018072; Conotoxin_a-typ_CS.
DR   Pfam; PF07365; Toxin_8; 1.
DR   PROSITE; PS60014; ALPHA_CONOTOXIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Acetylcholine receptor inhibitor; Amidation;
KW   Direct protein sequencing; Disulfide bond; Neurotoxin;
KW   Postsynaptic neurotoxin; Secreted; Signal; Sulfation; Toxin.
FT   SIGNAL        1     21       Potential.
FT   PROPEP       22     44
FT                                /FTId=PRO_0000034883.
FT   PEPTIDE      45     60       Alpha-conotoxin PnIB.
FT                                /FTId=PRO_0000034884.
FT   SITE         54     54       Direct interaction with nAChR alpha-7
FT                                subunit.
FT   MOD_RES      59     59       Sulfotyrosine.
FT   MOD_RES      60     60       Cysteine amide.
FT   DISULFID     46     52
FT   DISULFID     47     60
FT   MUTAGEN      54     54       L->A: Blocks nAChR alpha-7 subunits with
FT                                lower potency than PnIB and PnIA. Blocks
FT                                nAChR alpha-3/beta-2 subunits with a
FT                                potency range between the potency of PnIB
FT                                and PnIA.
FT   MUTAGEN      55     55       S->N: Blocks nAChr alpha-7 subunits with
FT                                higher potency than PnIB and PnIA. Blocks
FT                                nAChR alpha-3/beta-2 subunits with a
FT                                potency range between the potency of PnIB
FT                                and PnIA.
FT   HELIX        46     48
FT   HELIX        50     55
FT   TURN         57     59
SQ   SEQUENCE   61 AA;  6363 MW;  42E0033324D66922 CRC64;
     MGMRMMFTVF LLVVLATTVV SFTSDRASDD GNAAASDLIA LTIKGCCSLP PCALSNPDYC
     G
//