Ependymins and their potential role in neuroplasticity and regeneration: calcium-binding meningeal glycoproteins of the cerebrospinal fluid and extracellular matrix.

1. Ependymins are unique, highly divergent secretory proteins of the fish endomeninx. Thus far, no homologous sequences have been characterized in mammals. 2. Soluble ependymins are the predominant constituents of the cerebrospinal fluid of many teleost fish. A bound form of these glycoproteins is associated with the extracellular matrix probably with collagen fibrils. The latter may be the functional form of ependymins. 3. Ependymins bind Ca2+ via N-linked sialic acid residues leading to a conformational transition. 4. The molecular function of ependymins seems to be related to cell contact phenomena involving the extracellular matrix. For example, adhesive or anti-adhesive interactions may possibly influence ingrowing axons.