PHEROPHORINS - A FAMILY OF EXTRACELLULAR-MATRIX GLYCOPROTEINS FROM VOLVOX STRUCTURALLY RELATED TO THE SEX-INDUCING PHEROMONE

Pherophorins are extracellular matrix (ECM) glycoproteins from Volvox that share homology with the sex-inducing pheromone. A novel pherophor in (pherophorin III) was characterized both with respect to expression pattern and proteolytic processing in vivo. Furthermore, it was shown that the pherophorins represent a protein family of ECM glycoproteins exhibiting a modular composition: their N-terminally located domain i s a homolog of a domain found in the ECM glycoprotein SSG 185. Togethe r with SSG 185, pherophorin I is a main component of the cellular zone within the ECM. The Volvox genome contains a tandem arrangement of ge nes encoding pherophorin II-related polypeptides. Inhibition of proteo lytic processing of pherophorin II and III in vivo appears to result i n the suppression of sexual induction.