WIP1 (WPP domain-interacting protein 1) is a plant-specific, tail-anchored protein of the outer nuclear membrane in Arabidopsis thaliana and one of three redundant WIP paralogs (WIP1, WIP2, WIP3). It has a cytoplasmic N-terminal region with a coiled-coil domain, a single C-terminal transmembrane segment, and a short perinuclear-space tail that functions as a KASH-like domain. Through this tail WIP1 binds the SUN domain of the inner-nuclear-membrane proteins SUN1 and SUN2 (and the mid-SUN proteins), forming the plant SUN-WIP LINC bridge; SUN binding is required for WIP1 retention at the nuclear envelope. On the cytoplasmic side WIP1 partners with the tail-anchored WIT proteins: WIT2 recruits the actin motor myosin XI-i, so the SUN-WIP-WIT2-myosin XI-i complex transmits cytoplasmic force to the nuclear envelope and is required for the elongated shape of epidermal nuclei. WIPs, together with WIT1/WIT2, also anchor RanGAP1 (via its plant-specific WPP domain) at the nuclear envelope of undifferentiated root-tip cells. WIP1 also colocalizes with RanGAP1 at the cell plate, and binds the kinesin AtPSS1 in two-hybrid and BiFC assays. In pollen, SUN-anchored WIP-WIT complexes at the vegetative nuclear envelope are needed for vegetative nucleus migration, pollen tube guidance and reception, and male fertility; most phenotypes are seen only when WIP1, WIP2 and WIP3 are lost together.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005515 protein binding | IPI PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | REMOVE | Summary: Protein binding with the paralog WIP2 (abstract-only source). Reason: Generic protein binding is uninformative. The WIP1-WIP2 interaction (presumably two-hybrid in the full text) was not detected in planta in later co-IP work from the same laboratory, so it does not support a specific function. Removal does not dispute the reported interaction. Supporting Evidence: PMID:18591351 By contrast, WIP1 does not interact with itself ( Figure 2D ) or with either WIP2a or WIP3 in N. benthamiana leaves (data not shown). |
| GO:0005515 protein binding | IPI PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | MODIFY | Summary: Protein binding with RanGAP1 (in vivo interaction; colocalization at NE and cell plate). Reason: Generic protein binding is uninformative. WIPs anchor RanGAP1 (via its plant-specific WPP domain) at the nuclear envelope of root-tip cells; the wip1 wip2 wip3 triple mutant dislocates RanGAP1 from the NE. WIP1, an ONM protein, thus tethers a soluble protein to the membrane: GO:0043495 protein-membrane adaptor activity. Proposed replacements: protein-membrane adaptor activity Supporting Evidence: PMID:17600715 Arabidopsis WPP-domain interacting proteins (WIPs) that interact with RanGAP1 in vivo and colocalize with RanGAP1 at the NE and cell plate were identified. PMID:17600715 In a wip1-1/wip2-1/wip3-1 triple mutant, RanGAP1 is dislocated from the NE in undifferentiated root-tip cells file:ARATH/WIP1/WIP1-deep-research-falcon.md Co-immunoprecipitation showed that SUN2 associates with RanGAP1 only when WIP1 is coexpressed PMID:22270916 AtRanGAP1-GFP and RFP-Myc-AtSUN2 were coexpressed with either AtWIP1 or AtWIP1XT in N. benthamiana leaves. |
| GO:0005515 protein binding | IPI PMID:18591351 Two distinct interacting classes of nuclear envelope-associa... | MODIFY | Summary: Protein binding with WIT1; a WIP-WIT heterocomplex anchors RanGAP1 at the root-tip NE. Reason: Generic protein binding is uninformative. WIP1 increases WIT1-RanGAP1 binding and the WIP-WIT heterocomplex is the RanGAP1 anchor, so the informative function is membrane anchoring of RanGAP1 (GO:0043495). Proposed replacements: protein-membrane adaptor activity Supporting Evidence: PMID:18591351 suggesting that WIP1 increases the binding affinity of WIT1 and RanGAP1 PMID:18591351 the existence of a WIP-WIT heterocomplex required for anchoring RanGAP1 to the root tip NE is strongly supported |
| GO:0005515 protein binding | IPI PMID:19011093 RanGAP1 is a continuous marker of the Arabidopsis cell divis... | MODIFY | Summary: Protein binding with RanGAP1 (RanGAP1 division-plane marker study). Reason: The RanGAP1-WIP interaction depends on the RanGAP1 WPP domain; WIPs anchor RanGAP1 at the NE but are dispensable for its mitotic targeting. The informative MF is protein-membrane adaptor activity (GO:0043495). Proposed replacements: protein-membrane adaptor activity Supporting Evidence: PMID:19011093 Nevertheless, introducing the WPP to AAP mutation that disrupts binding to the WIP family disrupted all cellular targeting events. PMID:19011093 Arabidopsis RanGAP1 concentration at the nuclear envelope in nondifferentiated root tip cells is dependent on a group of nuclear pore-associated proteins (WIPs) |
| GO:0005515 protein binding | IPI PMID:20579133 A laboratory evaluation of the physical and mechanical prope... | MODIFY | Summary: Protein binding with RanGAP1, attributed by IntAct to PMID:20579133, which resolves to an unrelated dental-materials paper (root canal sealers). Reason: The cited PMID is a wrong identifier (see reference_review): the IntAct record (IMEx IM-19345) lists its source as 'Xu et al. (2007)', consistent with the WIP discovery paper PMID:17600715, but a separate IMEx id means this could not be confirmed and no replacement is asserted. The WIP1-RanGAP1 interaction itself is well established; as for the other RanGAP1 rows, the informative MF is GO:0043495. Proposed replacements: protein-membrane adaptor activity Supporting Evidence: PMID:17600715 Arabidopsis WPP-domain interacting proteins (WIPs) that interact with RanGAP1 in vivo and colocalize with RanGAP1 at the NE and cell plate were identified. |
| GO:0005515 protein binding | IPI PMID:22270916 Novel plant SUN-KASH bridges are involved in RanGAP anchorin... | MODIFY | Summary: Protein binding with AtSUN1: WIP1 binds SUN1 through its perinuclear-space (KASH-like) tail. Reason: The partner is an INM SUN protein and the interaction is the plant SUN-KASH bridge, required for WIP1 and RanGAP1 NE localization and nuclear shape. As for the human nesprin reviews, the informative function is GO:0140444 cytoskeleton-nuclear membrane anchor activity. Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:22270916 we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. PMID:22270916 AtWIP1 interacts with AtSUN1 through its PNS tail. PMID:22270916 both the exchange of the PNS tail and the deletion of VVPT greatly reduced binding between AtWIP1 and AtSUN1 |
| GO:0005515 protein binding | IPI PMID:22270916 Novel plant SUN-KASH bridges are involved in RanGAP anchorin... | MODIFY | Summary: Protein binding with AtSUN2 through the WIP1 PNS tail and the SUN2 SUN domain. Reason: Plant SUN-KASH bridge; GO:0140444 as for SUN1. Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:22270916 we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. PMID:22270916 AtSUN2 interacts with AtWIP1 through its SUN domain. |
| GO:0005515 protein binding | IPI PMID:23973298 Myosin XI-i links the nuclear membrane to the cytoskeleton t... | MODIFY | Summary: Protein binding with WIT1, from the myosin XI-i (KAKU1) nucleocytoplasmic linker study (abstract-only). Reason: In this study WIT proteins anchor myosin XI-i to the nuclear membrane and the WIP-WIT pair connects to SUN proteins, forming a plant nucleocytoplasmic linker for nuclear movement and shape. WIP1's role in this linker is the KASH-side anchor (GO:0140444). Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:23973298 Here, we describe a new type of nucleocytoplasmic linker consisting of a myosin motor and nuclear membrane proteins. |
| GO:0005515 protein binding | IPI PMID:23973298 Myosin XI-i links the nuclear membrane to the cytoskeleton t... | MODIFY | Summary: Protein binding with SUN2 (myosin XI-i linker study; abstract-only). Reason: SUN-WIP bridge; GO:0140444. Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:22270916 we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. |
| GO:0005515 protein binding | IPI PMID:25217773 Characterization of two distinct subfamilies of SUN-domain p... | MODIFY | Summary: Protein binding with the mid-SUN protein AtSUN3, which interacts with the KASH domain of AtWIP1. Reason: Both Cter-SUN and mid-SUN proteins bind the WIP1 KASH domain; the informative function is the KASH-side SUN-binding anchor (GO:0140444). Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:25217773 we demonstrated that both subfamilies interact with the KASH domain of AtWIP1 |
| GO:0005515 protein binding | IPI PMID:25330379 The kinesin AtPSS1 promotes synapsis and is required for pro... | MODIFY | Summary: Protein binding with the kinesin AtPSS1 (KIN-1), by yeast two-hybrid and BiFC. Reason: Generic protein binding is uninformative. The partner is a kinesin, shown by two assays (Y2H and BiFC in planta); GO:0019894 kinesin binding records this specifically without asserting the speculative force-transmission role proposed by the authors for meiosis. Proposed replacements: kinesin binding Supporting Evidence: PMID:25330379 Yeast two-hybrid experiments showed that AtPSS1 interacts directly with WIP1 and WIP2. PMID:25330379 The AtPSS1-WIP1 but not the AtPSS1-WIP2 interaction was confirmed by BiFC assays (Figure S5). |
| GO:0005515 protein binding | IPI PMID:25330379 The kinesin AtPSS1 promotes synapsis and is required for pro... | REMOVE | Summary: Protein binding with WIP2 (yeast two-hybrid in the AtPSS1 study). Reason: Generic protein binding is uninformative; WIP1-WIP2 interaction was not detected in planta in an earlier study. Removal does not dispute the two-hybrid result. Supporting Evidence: PMID:18591351 By contrast, WIP1 does not interact with itself ( Figure 2D ) or with either WIP2a or WIP3 in N. benthamiana leaves (data not shown). |
| GO:0005515 protein binding | IPI PMID:25759303 Plant nuclear shape is independently determined by the SUN-W... | MODIFY | Summary: Protein binding with WIT2, which recruits myosin XI-i to SUN-WIP bridges. Reason: WIP1 binds WIT2, which recruits the actin motor myosin XI-i to the SUN-WIP bridge to transfer cytoplasmic force to the NE for nuclear shape determination. WIP1's function is the KASH-side cytoskeleton-nuclear membrane anchor (GO:0140444). Proposed replacements: cytoskeleton-nuclear membrane anchor activity Supporting Evidence: PMID:25759303 We show that WIT2, but not WIT1, plays an essential role in nuclear shape determination by recruiting myosin XI-i to the SUN-WIP NE bridges. |
| GO:0005515 protein binding | IPI PMID:32612234 Extensive signal integration by the phytohormone protein net... | REMOVE | Summary: Protein binding with the ABA receptor PYL9, from a large-scale phytohormone protein interaction network (abstract-only). Reason: Generic protein binding from a high-throughput two-hybrid network is uninformative and has no functional follow-up for WIP1. Removal does not dispute the interaction. |
| GO:0005635 nuclear envelope | IBA GO_REF:0000033 | ACCEPT | Summary: Nuclear envelope (IBA, WIP family node PTN002159747). Reason: WIP1-3 are ONM proteins of the plant nuclear envelope. Supporting Evidence: PMID:17600715 Immunogold labeling indicates that WIP1 is associated with the outer NE. |
| GO:0005635 nuclear envelope | IDA PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | ACCEPT | Summary: Nuclear envelope; immunogold places WIP1 on the outer nuclear envelope. Reason: Correct. The same study localizes WIP1 more precisely to the outer nuclear membrane, proposed as a NEW annotation (GO:0005640). Supporting Evidence: PMID:17600715 Immunogold labeling indicates that WIP1 is associated with the outer NE. |
| GO:0005635 nuclear envelope | IDA PMID:22270916 Novel plant SUN-KASH bridges are involved in RanGAP anchorin... | ACCEPT | Summary: Nuclear envelope; SUN binding is required for WIP1 NE localization. Reason: Direct evidence. Supporting Evidence: PMID:22270916 we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. |
| GO:0005635 nuclear envelope | IEA GO_REF:0000044 | ACCEPT | Summary: Nuclear envelope (UniProt mapping). Reason: Correct. Supporting Evidence: PMID:17600715 Immunogold labeling indicates that WIP1 is associated with the outer NE. |
| GO:0006997 nucleus organization | IBA GO_REF:0000033 | ACCEPT | Summary: Nucleus organization (IBA). Reason: SUN-WIP bridges, with WIT2-myosin XI-i, determine the elongated shape of epidermal nuclei; WIPs contribute structurally to this. Supporting Evidence: PMID:22270916 AtWIPs and AtSUNs are necessary for maintaining the elongated nuclear shape of Arabidopsis epidermal cells. |
| GO:0006997 nucleus organization | IGI PMID:22270916 Novel plant SUN-KASH bridges are involved in RanGAP anchorin... | ACCEPT | Summary: Nucleus organization (IGI with SUN1/SUN2): wip and sun mutants have rounder epidermal nuclei. Reason: Core process: WIP1 is the ONM component of the bridge transmitting cytoplasmic (myosin XI-i) force to the NE to shape the nucleus. Supporting Evidence: PMID:22270916 AtWIPs and AtSUNs are necessary for maintaining the elongated nuclear shape of Arabidopsis epidermal cells. PMID:25759303 We show that WIT2, but not WIT1, plays an essential role in nuclear shape determination by recruiting myosin XI-i to the SUN-WIP NE bridges. file:ARATH/WIP1/WIP1-deep-research-falcon.md substantial paralog redundancy is a central annotation constraint |
| GO:0009504 cell plate | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Cell plate (IBA). Reason: WIPs colocalize with RanGAP1 at the cell plate, but WIPs are dispensable for RanGAP1 targeting to the cell plate; a genuine but non-core location. Supporting Evidence: PMID:17600715 Arabidopsis WPP-domain interacting proteins (WIPs) that interact with RanGAP1 in vivo and colocalize with RanGAP1 at the NE and cell plate were identified. PMID:19011093 However, WIPs appear dispensable for RanGAP1 phragmoplast midline/cell plate targeting during cytokinesis |
| GO:0009504 cell plate | IDA PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | KEEP AS NON CORE | Summary: Cell plate (colocalization with RanGAP1). Reason: Direct localization, but no function at the cell plate has been shown (RanGAP1 cell plate targeting is WIP-independent). Supporting Evidence: PMID:17600715 Arabidopsis WPP-domain interacting proteins (WIPs) that interact with RanGAP1 in vivo and colocalize with RanGAP1 at the NE and cell plate were identified. |
| GO:0031965 nuclear membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Nuclear membrane (UniProt mapping). Reason: Correct; WIP1 is a single-pass protein of the outer nuclear membrane. Supporting Evidence: PMID:17600715 Immunogold labeling indicates that WIP1 is associated with the outer NE. |
| GO:0042803 protein homodimerization activity | IPI PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | UNDECIDED | Summary: Protein homodimerization activity (abstract-only source). Reason: The original evidence (presumably two-hybrid) is not visible in the abstract, and a later study from the same laboratory found no WIP1 self-interaction in planta (co-IP in N. benthamiana) or in a heterologous assay, although WIP1 has a coiled-coil region and the authors still invoke a low-abundance WIP1 dimer. Evidence is conflicting and the full text of the source is unavailable. Supporting Evidence: PMID:18591351 By contrast, WIP1 does not interact with itself ( Figure 2D ) or with either WIP2a or WIP3 in N. benthamiana leaves (data not shown). PMID:18591351 While capable of interacting with WIT1, WIP1 did not show homodimerization ability in the same assay ( Figure 2D ). |
| GO:0046982 protein heterodimerization activity | IPI PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | UNDECIDED | Summary: Protein heterodimerization activity with WIP2 (abstract-only source). Reason: As for homodimerization: WIP1 interaction with WIP2a/WIP3 was not detected in planta in later work, and the original assay cannot be inspected. Supporting Evidence: PMID:18591351 By contrast, WIP1 does not interact with itself ( Figure 2D ) or with either WIP2a or WIP3 in N. benthamiana leaves (data not shown). |
| GO:0005640 nuclear outer membrane | IDA PMID:17600715 Anchorage of plant RanGAP to the nuclear envelope involves n... | NEW | Summary: Nuclear outer membrane: immunogold electron microscopy places WIP1 at the outer nuclear envelope. Reason: The defining location of a KASH-side LINC protein; directly observed by immunogold EM and consistent with SUN binding of its perinuclear tail. Human nesprin reviews use GO:0005640 for the same role. Supporting Evidence: PMID:17600715 Immunogold labeling indicates that WIP1 is associated with the outer NE. PMID:22270916 we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. |
Loading supporting content…
Download this section (compressed HTML)Q: The plant SUN-WIP(-WIT-myosin XI-i) bridge couples the nucleus to actin rather than microtubules. Should it be annotated to GO:0106094 nuclear membrane microtubule tethering complex, or does GO need a generic LINC complex term (not microtubule-specific) that plant SUN-WIP complexes can use?
Suggested experts: GO cellular component editors, TAIR curators
Q: SUN-anchored WIP-WIT complexes are required for pollen vegetative-nucleus migration (PMID:26409047), but the evidence is from dominant-negative SUN2 and wip1 wip2 wip3 wit1 wit2 quintuple mutants. Should WIP1 carry a nuclear migration process term (e.g. GO:0007097), or should this wait for paralog-resolved evidence?
Suggested experts: plant nuclear envelope biologists
Q: Is WIP1 homodimerization real in planta, given conflicting two-hybrid and co-IP results?
Suggested experts: Meier lab, TAIR curators
Experiment: Structure or crosslinking analysis of AtSUN2 SUN domain with the WIP1 perinuclear tail (ending in VVPT) to compare with the canonical SUN-KASH PPPX groove interaction.
Hypothesis: The WIP KASH-like tail binds the SUN groove analogously to animal KASH peptides despite divergent sequence.
Type: structural biology
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)