{PDOC60020} {PS60020; J_ACTX} {BEGIN} ***************************************************** * Janus-faced atracotoxin (J-ACTX) family signature * ***************************************************** Janus-faced atracotoxins (J-ACTXs) form a family of insecticidal neurotoxins isolated from the venom of one of the world's most lethal arachnids, the Blue mountains funnel-web spider Hadronyche versuta. J-ACTXs are 36 or 37 residues in length with eight conserved cysteine residues involved in four disulfide bonds, including an extemely rare vicinal disulfide (a disulfide bond between adjacent cysteine residues) that has been shown to be essential for insecticidal activity. J-ACTXs possess two strikingly dissimilar faces. One face presents an almost contiguous charged surface, while the opposing face containing the vicinal disulfide is devoid of ionizable side chains [1]. J-ACTX family proteins have a [C-C-CC-CC-C-C] cysteine arrangement, which is similar to that of the I-superfamily conotoxins (see ). The three dimensional structure of J-ACTXs possesses a knottin scaffold (see ) [E1] and III-IV pair of cysteine residues (as marked '#' in schematic representation) involved in a additional disulfide linkage. The cysteine knot motif in J-ACTXs provides high stability and maintains the tertiary structure. +----------------+ ## | | CxxxxxxCxxCCxCCxxxxCxxxxxxxxxxC | | | | +------|------+ | +-----------+ 'C': conserved cysteine involved in disulfide bond. '#': Cysteines three and four are connected to each other through a disulfide bond. Our signature pattern for J-ACTXs contains the eight conserved cysteines involved in disulfide bonds. -Conserved pattern: C-{C}(6)-C-x(2)-C-C-x-C-C-x(4)-C-x(9,10)-C [The 8 C's are involved in disulfide bonds] -Sequences known to belong to this class detected by the pattern: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Expert(s) to contact by email: Ramakumar S.; ramak@physics.iisc.ernet.in -Last update: July 2005 / First entry. [ 1] Wang X., Connor M., Smith R., Maciejewski M.W., Howden M.E.H., Nicholson G.M., Christie M.J., King G.F. "Discovery and characterization of a family of insecticidal neurotoxins with a rare vicinal disulfide bridge." Nat. Struct. Biol. 7:505-513(2000). PubMed=10881200; DOI=10.1038/75921 [E1] https://bioserv.cbs.cnrs.fr -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}