Contactin is a neural cell adhesion molecular that is tethered to the cell surface through a glycosyl phosphatidylinositol (GPI)-linked anchor. Although it has been reported to be in a complex with the intracellular tyrosine kinase fyn, the nature of this interaction has not been clear. Zeng et al. propose that a receptor-type protein tyrosine phosphatase, PTPα, could be an intermediate component in this complex. The authors show that endogenous contactin and PTPα in chick brain can be isolated in a complex. The two proteins also colocalized when overexpressed in cultured cells. Because this interaction was not detected when cells expressing either protein were cultured together, the authors suggest that interaction occurs as a receptor complex within the same cell. The finding suggests possible signaling through a contactin-PTPα complex, as PTPα is also thought to signal through fyn in developing neural tissue. A tripartite complex of contactin, PTPα, and fyn, as well as the physiological significance of this interaction, has yet to be determined.
Zeng, L., D'Alessandri, L., Kalousek, M.B., Vaughan, L., and Pallen, C.J. (1999) Protein tyrosine phosphataseα (PTPα) and contactin form a novel neuronal receptor complex linked to the intracellular tyrosine kinase fyn. J. Cell Biol. 147: 707-714. [Abstract] [Full Text]