Fig. 9. Model illustrating the interactions of Sun1 with Nesprins at the nuclear envelope. Unknown nuclear envelope proteins and interactions are indicated by X and?, respectively. To reduce complexity a homotypic dimerisation of Sun1 via the coiled-coil regions is postulated, although other coiled-coil-containing proteins might form heterotypic complexes with Sun1. INM, inner nuclear membrane; LD, luminal domain; N, N-terminal domain; ONM, outer nuclear membrane; PNS, perinuclear space.