Immunological Identification of a Putative Precursor of the Insoluble Glycoprotein Framework of the Chlamydomonas Cell Wall

To identify precursors of the insoluble glycoprotein frameworkof the Chlamydomonas cell wall, a polyclonal antibody was raisedagainst the mixture of polypeptides released from the insolublewall fraction by chemical deglycosylation. This antibody preferentiallycross-reacted with a ‘150 kDa’ salt-soluble cellwall glycoprotein. The conclusion that this ‘150 kDa’glycoprotein is a putative precursor of the insoluble cell wallfraction was corroborated by the results of pulse-chase experimentsand by experiments with antibodies raised against the ‘150kDa’ salt-soluble glycoprotein and against its 100 kDadeglycosylation product, respectively. Whereas the antibodyagainst the ‘150 kDa’ glycoprotein preferentiallyrecognized carbohydrate side chains, the antibody against its100 kDa deglycosylation product was found to have essentiallythe same specificity towards glycosylated and deglycosylatedcell wall components as the antibody against the deglycosylationproducts of the insoluble wall fraction. Furthermore, the antibodyagainst the deglycosylated, insoluble wall fraction recognizedalmost the same set of peptide fragments derived by V8 proteasetreatment from the ‘150 kDa’ salt-soluble cell wallglycoprotein and its 100 kDa deglycosylation product, respectively,as the antibody against the 100 kDa deglycosylated cell wallpolypeptide. (Received April 22, 1994; Accepted November 21, 1995)