Going green: plants' alternative way to position the Ran gradient.

摘要: Ran is a multi-functional small GTPase of the Ras super-family involved in nucleocytoplasmic transport, mitotic spindle assembly, cell cycle control and nuclear envelope (NE) formation. Its roles are accomplished by asymmetric distribution its GTP- GDP-bound forms, enabled specific localization accessory proteins, GTPase-activating protein RanGAP nucleotide exchange factor RCC1. Mammalian RanGAP1 targeted to NE during interphase kinetochores mitosis via SUMOylated C-terminal domain interaction with nucleoporin Nup358/RanBP2. Arabidopsis (AtRanGAP1) lacks vertebrate RanGAP, but contains plant-specific N-terminal (WPP domain), which necessary sufficient for targeting interphase. AtRanGAP1 has trafficking pattern uniquely different from that includes outward-growing rim plate. The WPP this targeting. Now, novel family plant-specific, pore-associated proteins been identified Arabidopsis, essential anchoring at root meristem. This suggests pore solved two fundamentally ways animals plants. These findings support separate evolution mechanisms kingdoms, possibly related functional geometries gradient animal higher plant division.