PDBsum entry: 1qva

Gene regulation

PDB id: 1qva

Contents

Protein chain

213 a.a. *

Waters ×55

* Residue conservation analysis

PDB id:

1qva

Name:

Gene regulation

Title:

Yeast initiation factor 4a n-terminal domain

Structure:

Initiation factor 4a. Chain: a. Fragment: residues 2-224. Synonym: eif-4a, stimulator factor i 37, kd component. Engineered: yes

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.50Å R-factor: 0.223 R-free: 0.274

Authors:

E.R.Johnson,D.B.Mckay

Key ref:

R.Romi-Lebrun et al. (1997). Purification, characterization, and synthesis of three novel toxins from the Chinese scorpion Buthus martensi, which act on K+ channels. Biochemistry, 36, 13473-13482. PubMed id: 9354615 DOI: 10.1021/bi971044w

Date:

07-Jul-99 Release date: 02-Dec-99

Protein chain

P10081  (IF4A_YEAST) -  ATP-dependent RNA helicase eIF4A

Seq: 395 a.a.

Struc: 213 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.6.4.13 - Rna helicase.
• Reaction: ATP + H₂O = ADP + phosphate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Biochemical function: nucleic acid binding (3 terms)

reference

DOI no: 10.1021/bi971044w

Biochemistry 36:13473-13482 (1997)

PubMed id: 9354615

Purification, characterization, and synthesis of three novel toxins from the Chinese scorpion Buthus martensi, which act on K+ channels.

R.Romi-Lebrun, B.Lebrun, M.F.Martin-Eauclaire, M.Ishiguro, P.Escoubas, F.Q.Wu, M.Hisada, O.Pongs, T.Nakajima.

ABSTRACT

Three novel toxins belonging to the scorpion K+ channel-inhibitor family were purified to homogeneity from the venom of the Chinese scorpion Buthus martensi. They have been identified according to their molecular mass (3800-4300 Da) and their neurotoxicity in mice and characterized as 37-amino acid peptides. One of them shows 81-87% sequence identity with members of the kaliotoxin group (named BmKTX), whereas the other two, named BmTX1 and BmTX2, show 65-70% identity with toxins of the charybdotoxin group. Their chemical synthesis by the Fmoc methodology allowed us to show that BmKTX, unlike BmTX1 and BmTX2, possesses an amidated C-terminal extremity. Toxicity assays in vivo established that they are lethal neurotoxic agents in mice (LD50s of 40-95 ng per mouse). Those toxins proved to be potent inhibitors of the voltage-gated K+ channels, as they were able to compete with [125I]kaliotoxin for its binding to rat brain synaptosomes (IC50s of 0.05-1 nM) and to block the cloned voltage-gated K+ channel Kv1.3 from rat brain, expressed in Xenopus oocytes (IC50s of 0.6-1.6 nM). BmTX1 and BmTX2 were also shown to compete with [125I]charybdotoxin for its binding to the high-conductance Ca2+-activated K+ channels present on bovine aorta sarcolemmal membranes (IC50s of 0.3-0.6 nM). These new sequences show multipoint mutations when compared to the other related scorpion K+ channel toxins and should prove to be useful probes for studying the diverse family of K+ channels.