Figure 10.

Three potential models for UNC-84 function during nuclear migration. A cross section of the nuclear envelope is depicted with one nuclear pore complex. The two domains of UNC-84 protein are depicted as a black circle and black triangle, one on each side of the inner nuclear membrane (INM). The plus ends of three microtubules (MT) are shown extending from the centrosome. In the gene expression model, UNC-84 forms a complex with one or more partners (X, Y), to either activate or repress genes that directly mediate nuclear migration. In the signaling model, UNC-84 could act alone or with partner X (depicted as an integral membrane protein) to regulate protein Y, which either activates or inhibits migration. In the bridging model, UNC-84 is located on either the inner or outer nuclear membrane, and interacts with the lumenal domain of protein X, in the opposing membrane. In either case, the protein on the inner membrane binds directly to lamins.