Peptidase M28 family, Nicalin (nicastrin-like protein) subfamily. Nicalin is distantly related to Nicastrin, a component of the Alzheimer's disease-associated gamma-secretase, and forms a complex with Nomo (nodal modulator) pM5. Similar to Nicastrin, Nicalin lacks the amino-acid conservation required for catalytically active aminopeptidases. Functional studies in zebrafish embryos and cultured human cells reveal that nicalin and Nomo collaborate to antagonize the Nodal/TGFbeta signaling pathway. Thus, nicastrin and nicalin are both associated with protein complexes involved in cell fate decisions during early embryonic development.