Scorpion toxins that block transient currents (I(A)) of rat cerebellum granular cells.
This communication is a revision of the state-of-the-art knowledge of the field of scorpion toxins specific for the K(+)-channels, responsible for the I(A) currents of granular cells of rat cerebellum, maintained in vitro culture. There are 6 members of the sub-family alpha-KTx15 known to affect the I(A) currents. They are: toxins Aa1 from Androctonus australis Garzoni, BmTx3 from Buthusmartensi Karch, AmmTx3 from Androctonus mauretanicus mauretanicus, AaTx1 and AaTx2 from A. australis Garzoni and Discrepin from Tityus discrepans. They share high sequence similarity, apart from Discrepin, which causes an irreversible effect on the I(A) currents and is the most thoroughly studied toxin of the sub-family alpha-KTx15. The three-dimensional structure of Discrepin was determined and a series of mutants were synthesized and assayed in the system with the aim of identifying possible amino acids or sequence segments responsible for the irreversible effect found. In this revision some unpublished original data are also included to foster future work on the field, as well as a short discussion on some relevant aspects still pending and possible limitations associated with the strategy proposed.
Institute of Biophysics, CNR, Via de Marini 6, 16149 Genoa, Italy. prestipino@ge.ibf.cnr.it
Gianfranco
G
Prestipino
Gerardo
G
Corzo
Stefania
S
Romeo
Anna Rosa
AR
Murgia
Ilaria
I
Zanardi
Georgina B
GB
Gurrola
Lourival D
LD
Possani
D000595:Amino Acid Sequence; D000818:Animals; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects*; D008969:Molecular Sequence Data; D009154:Mutation; D009498:Neurotoxins / Q000737:chemistry / Q000633:toxicity*; D026902:Potassium Channel Blockers / Q000737:chemistry / Q000633:toxicity*; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000187:drug effects*; D011487:Protein Conformation; D051381:Rats; D012604:Scorpion Venoms / Q000737:chemistry / Q000235:genetics / Q000633:toxicity*
D009498:Neurotoxins; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms; C509989:discrepin protein, Tityus discrepans