IMMUNOLOGICAL IDENTIFICATION OF A PUTATIVE PRECURSOR OF THE INSOLUBLEGLYCOPROTEIN FRAMEWORK OF THE CHLAMYDOMONAS CELL-WALL

To identify precursors of the insoluble glycoprotein framework of the Chlamydomonas cell wall, a polyclonal antibody was raised against the mixture of polypeptides released from the insoluble wall fraction by c hemical deglycosylation. This antibody preferentially cross-reacted wi th a '150 kDa' salt-soluble cell wall glycoprotein. The conclusion tha t this '150 kDa' glycoprotein is a putative precursor of the insoluble cell wall fraction was corroborated by the results of pulse-chase exp eriments and by experiments with antibodies raised against the '150 kD a' salt-soluble glycoprotein and against its 100 kDa deglycosylation p roduct, respectively. Whereas the antibody against the '150 kDa' glyco protein preferentially recognized carbohydrate side chains, the antibo dy against its 100 kDa deglycosylation product was found to have essen tially the same specificity towards glycosylated and deglycosylated ce ll wall components as the antibody against the deglycosylation product s of the insoluble wall fraction. Furthermore, the antibody against th e deglycosylated, insoluble wall fraction recognized almost the same s et of peptide fragments derived by V8 protease treatment from the '150 kDa' salt-soluble cell wall glycoprotein and its 100 kDa deglycosylat ion product, respectively, as the antibody against the 100 kDa deglyco sylated cell wall polypeptide.