Calsyntenin


Calsyntenins are type I transmembrane proteins that belong to the cadherin superfamily. Their name comes from their ability to bind calcium. In birds and mammals, they consist of three family members, in nematodes one ortholog is known.
Cst1 was first shown to be predominantly expressed in postsynaptic membranes of excitatory neurons, Cst2 and 3 were found in an increased manner in inhibitory GABAergic neurons, in adult and embryonic tissue. Calsyntenins interact with numerous proteins such as with kinesin-1 and the APP-linker protein X11L/Mint2, and were shown to have multi-purpose functions both within and outside the nervous system.
Shortly after the calsyntenins were discovered, they were found to regulate postsynaptic calcium concentration. Later it was found that another key-function is to link vesicles to kinesin light chain and thus to co-determine transport of distinct cargo.. Recent studies identified a role for calsyntenin 1 in the regulation of vesicular trafficking of guidance receptors in dI1 axons at choice points. In cooperation with RabGDI, calsyntenin 1 shuttles Rab11-positive vesicles containing Robo1 to the growth cone surface in a precisely regulated manner. By contrast, calsyntenin 1-mediated trafficking of frizzled 3, a guidance receptor in the Wnt pathway, is independent of RabGDI. Calsyntenin gene expression also elevates during oxidative stress in PC12 cells