Two Classes of Proteins and mRNAs in Lilium longiflorum L. Identified by Human Vitronectin Probes

Vitronectin (VN) is a substrate adhesion molecule, an extracellular matrix glycoprotein that facilitates cell adhesion and cell movement in animals. We have reported the cross-reactivity of a 55-kD protein in plants with rabbit anti-human VN antibodies and the presence of VN-like sequences in plant genomes using a human VN cDNA probe. We have extended these studies by using human VN riboprobes to detect VN-like mRNAs in lily (Lilium longiflorum L.) and soybean. In both species, two mRNAs were detected. We have also identified a new cross-reactive protein (41 kD) using a different preparation of human VN antiserum. In lily roots five 41-kD isoforms were observed, whereas only three of these isoforms accumulated in leaves. Monospecific antibodies prepared against the plant proteins cross-reacted with the human VN protein and vice versa. We have purified the 41-kD protein using two-dimensional gel electrophoresis, and amino acid composition analysis indicates that it is similar in composition to human VN.