Identification of a highly conserved hydroxyproline-rich glycoprotein in the cell walls ofChlamydomonas reinhardtiiand two other Volvocales

摘要

The unicellular algaChlamydomonas reinhardtiiDang, has a cell wall made entirely from hydroxyproline-rich glycoproteins (HRGPs). We recently employed a quantiative in vitro reconstitution system (Adair et al. 1987, J. Cell Biol.105, 2373–2382) to assign outer-wall HRGPs ofC. reinhardtiito specific sublayers, and describe the major interactions responsible for their assembly. Some of these interactions appear to involve relatively conserved HRGP domains, as evidenced by interspecific cell-wall reconstitution betweenC. reinhardtiiand two multicellular Volvocales (Volvoxcarterilyengar andGonium pectoraleMüller). In the present report we provide biochemical and immunological evidence that the outer cell-walls ofV. carteriandG. pectoraleboth contain prominent HRGPs closely related toC. reinhardtiiGP2. Identification of conserved GP2 homologues indicates a molecular basis for interspecific reconstitution and provides a useful avenue for characterization of HRGP domains mediating cell-wall formation in these alg