Ubiquitin and ubiquitination in cells from the marine sponge Geodia cydonium.

Marine sponges, e.g. Geodia cydonium, have been intensively used to investigate the biochemical and molecular biological basis of cell-cell- and cell-matrix adhesion. It has been shown that a family of galactose-specific lectins, which are present in the extracellular space of G. cydonium, is a main component involved in cell-matrix adhesion in the sponge system. In the present study it is outlined that the purified 16-kDa lectin-1 binds to a 67-kDa membrane-associated protein. This lectin-binding protein undergoes mono- and diubiquitination after incubation of dissociated sponge cells with the homologous aggregation factor (AF), a molecule involved in cell-cell adhesion. The gene coding fo…