The product of the cornichon gene was originally identified as being required for correct growth factor signaling during oogenesis [24]. Follow-up studies in drosophila, chicken and transfected culture cells identified cornichon and its orthologues as endoplasmic reticulum (ER) cargo exporters for members of the transforming growth factor α (TGFα) family [25]–[27]. In agreement with these studies, Shi and co-workers have recently suggested that CNIH-2 may exert a chaperone-like function facilitating the surface transport of AMPARs; the physiological relevance of the CNIH-2-mediated effects on receptor gating was questioned, as the authors failed to detect CNIH-2 on the cell surface of neurons [28]. In contrast, Kato et al. using an elegant biophysical approach together with immunocytochemistry demonstrated that CNIH-2 co-assembles into postsynaptic AMPAR complexes and modulates channel gating, pharmacology and association of GluA and TARP subunits [16], [29].
