Figure 11.

Proposed Model for the Function of Cnx1 in Moco Biosynthesis in Plant Cells.

Cnx1 is located under the plasmalemma and is bound to an actin filament. The interaction of Cnx1 with an integral membrane protein is based on the function described for the Cnx1-homologous animal protein gephyrin in neuroreceptor anchoring and needs to be verified. We propose an unidentified molybdate transport system that interacts with Cnx1 to facilitate substrate channeling to the E domain, given that a mutation in this part of the protein results in a molybdate-repairable phenotype. The conversion of precursor Z to MPT by the MPT synthase (Cnx6 and Cnx7) and the sulfurase (Cnx5) is shown. Because MPT is highly sensitive to oxidation, we suggest that the rapid conversion of precursor Z to Moco occurs in a multienzyme complex anchored by Cnx1 on the cytoskeleton.