Mac Lee, a student in the department of Life Sciences, was bitten by a snake in the backyard of life
science building. He was so angry! Thus, he killed the snake and purified several toxins from its
venoms. He sequenced one of the toxin, got this sequence:
1 L K C N K L V P L F Y K T C P A G K N I C Y K M F M V A T P
31 K L P V K R G C I D V C P K S S L L V R Y V C C N T D K C N
(1) Is this a new toxin? Please help him to identify this toxin.
(2) Can you find proteins that share sequence homology with this toxin? Show them (at least 10
sequences) in multiple alignment form (in color).
(3) He would like to see 3D structure of this toxin. Please help him to make the model.
(1)Blast with NCBI, the sequence that Mac Lee sequenced should be cytotoxin 3-chinese cobra.
The full query result are shown as below:
LOCUS 69484 60 aa 28-OCT-1994
DEFINITION cytotoxin 3 - Chinese cobra.
ACCESSION 69484
PID g69484
DBSOURCE PIR: locus H3NJ3F
summary: #length 60 #molecular-weight 6747 #checksum 7847.
superfamily: snake toxin.
PIR dates: 13-Jul-1981 #sequence_revision 13-Jul-1981 #text_change
28-Oct-1994.
KEYWORDS cytotoxin.
SOURCE Chinese cobra.
ORGANISM Naja atra
Eukaryotae; mitochondrial eukaryotes; Metazoa; Chordata;
Vertebrata; Lepidosauria; Squamata; Scleroglossa; Serpentes;
Colubroidea; Elapidae; Elapinae; Naja.
REFERENCE 1 (residues 1 to 60)
AUTHORS Narita,K. and Lee,C.Y.
TITLE The amino acid sequence of cardiotoxin from Formosan cobra (Naja
naja atra) venom
JOURNAL Biochem. Biophys. Res. Commun. 41 (2), 339-343 (1970)
MEDLINE 71211413
REFERENCE 2 (residues 1 to 60)
AUTHORS Hayashi,K., Takechi,M., Kaneda,N. and Sasaki,T.
TITLE Amino acid sequence of cardiotoxin from the venom of Naja naja atra
JOURNAL FEBS Lett. 66 (2), 210-214 (1976)
MEDLINE 76257817
FEATURES Location/Qualifiers
source 1..60
/organism="Naja atra"
/db_xref="taxon:8656"
Protein 1..60
/note="cardiotoxin analog III"
/product="cytotoxin 3"
Bond bond(3,21)
/bond_type="disulfide"
Bond bond(14,38)
/bond_type="disulfide"
Bond bond(42,53)
/bond_type="disulfide"
Bond bond(54,59)
/bond_type="disulfide"
ORIGIN
1 lkcnklvplf yktcpagknl cykmfmvatp kvpvkrgcid vcpkssllvk yvccntdrcn
61
//
(2) The proteins I selected are shown below:
SWISSPROT:CX2_NAJAT OS NAJA ATRA (CHINESE COBRA).SWISSPROT:CX1_NAJOX OS NAJA OXIANA (CENTRAL ASIAN COBRA) (OXUS COBRA).SWISSPROT:CX1_NAJNI OS NAJA NIVEA (CAPE COBRA).SWISSPROT:CX1_NAJNA OS NAJA NAJA (INDIAN COBRA).SWISSPROT:CX1D_NAJAT OS NAJA ATRA (CHINESE COBRA).SWISSPROT:CX1C_NAJAT OS NAJA ATRA (CHINESE COBRA).SWISSPROT:CX1B_NAJAT OS NAJA ATRA (CHINESE COBRA).SWISSPROT:CX10_NAJHA OS NAJA HAJE ANNULIFERA (BANDED EGYPTIAN COBRA).
