title: Targeting proteins to the plant nuclear envelope.
abstract: The nuclear envelope and the nuclear pore are important structures that both separate and selectively connect the nucleoplasm and the cytoplasm. The requirements for specific targeting of proteins to the plant nuclear envelope and nuclear pore are poorly understood. How are transmembrane-domain proteins sorted to the nuclear envelope and nuclear pore membranes? What protein-protein interactions are involved in associating other proteins to the nuclear pore? Are there plant-specific aspects to these processes? We are using the case of the nuclear pore-associated Ran-cycle component RanGAP (Ran GTPase-activating protein) to address these fundamental questions. Plant RanGAP is targeted to the nuclear pore by a plant-specific mechanism involving two families of nuclear pore-associated proteins [WIP (WPP-domain-interacting protein) and WIT (WPP-domain-interacting tail-anchored protein)] not found outside the land plant lineage. One protein family (WIP or WIT) is sufficient for RanGAP targeting in differentiated root cells, whereas both families are necessary in meristematic cells. A C-terminal predicted transmembrane domain is sufficient for targeting WIP proteins to the nuclear envelope. Nuclear-envelope targeting of WIT proteins requires a coiled-coil domain and is facilitated by HSC70 (heat-shock cognate 70 stress protein) chaperones and a class of plant-specific proteins resembling the RanGAP-targeting domain (WPP proteins). Taken together, this sheds the first light on the requirements and interdependences of nuclear envelope and nuclear pore targeting in land plants.
authors.affiliation: Department of Plant Cellular and Molecular Biology and Plant Biotechnology Center, The Ohio State University, Columbus, OH 43210, USA. meier.56@osu.edu
authors.forename: Iris
authors.initials: I
authors.lastname: Meier
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhou
authors.forename: Jelena
authors.initials: J
authors.lastname: Brkljacić
authors.forename: Annkatrin
authors.initials: A
authors.lastname: Rose
authors.forename: Qiao
authors.initials: Q
authors.lastname: Zhao
authors.forename: Xianfeng Morgan
authors.initials: XM
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D010940:Plant Proteins; C501409:WPP1 protein, Arabidopsis