A STYLE-SPECIFIC HYDROXYPROLINE-RICH GLYCOPROTEIN WITH PROPERTIES OF BOTH EXTENSINS AND ARABINOGALACTAN PROTEINS

A basic, hydroxyproline-rich glycoprotein (molecular mass 120 kDa) has been purified from the styles of Nicotiana alata. An antibody, specif ic for the protein backbone (molecular mass 78 kDa) of the glycoprotei n, was used to demonstrate that the glycoprotein is a soluble, style-s pecific component and that related molecules are present in the styles of other solanaceous species. Linkage analysis of the carbohydrate po rtion of the glycoprotein, together with antibody binding studies, ind icates that the glycoprotein contains both extensin-like and arabinoga lactan-protein (AGP)-like side chains. Furthermore, the AGP-like side- chains contain a style-specific epitope that is also present on AGPs f rom N. alata styles and glycoconjugates from the styles of other membe rs of the Solanaceae. The abundance of this 120 kDa glycoprotein, its location in the extracellular matrix of the transmitting tract and its conservation in several species within the Solanaceae suggests a role in pistil function.