Structure of the snake-venom toxin convulxin

Snake venoms contain a number of proteins that interact with components of the haemostatic system that promote or inhibit events leading to blood- clot formation. The snake- venom protein convulxin ( Cvx) binds glycoprotein ( GP) VI, the platelet receptor for collagen, and triggers signal transduction. Here, the 2.7 Angstrom resolution crystal structure of Cvx is presented. In common with other members of this snake-venom protein family, Cvx is an alphabeta- heterodimer and conforms to the C- type lectin- fold topology. Comparison with other family members allows a set of Cvx residues that form a concave surface to be putatively implicated in GPVI binding. Unlike other family members, with the exception of flavocetin- A ( FL- A), Cvx forms an (alphabeta)(4) tetramer. This oligomeric structure is consistent with Cvx clustering GPVI molecules on the surface of platelets and as a result promoting signal transduction activity. The Cvx structure and the location of the putative binding sites suggest a model for this multimeric signalling assembly.

An overview of the PETS 2009 challenge

This paper describes the crowd image analysis challenge that forms part of the PETS 2009 workshop. The aim of this challenge is to use new or existing systems for i) crowd count and density estimation, ii) tracking of individual(s) within a crowd, and iii) detection of separate flows and specific crowd events, in a real-world environment. The dataset scenarios were filmed from multiple cameras and involve multiple actors.