BIK1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0004672 protein kinase activity	IEA GO_REF:0000002	MODIFY	Summary: BIK1 is a catalytically active protein kinase; this InterPro-based electronic annotation is correct but less specific than the experimentally supported Ser/Thr kinase terms. Reason: Correct but general. BIK1 is a proven Ser/Thr (dual-specificity) protein kinase (EC 2.7.11.1); the more specific term protein serine/threonine kinase activity is preferred and is independently supported by experimental annotations. Proposed replacements: protein serine/threonine kinase activity Supporting Evidence: PMID:24104392 we identified nineteen in vitro autophosphorylation sites of BIK1 including three phosphotyrosine sites, thereby proving BIK1 is a dual-specificity kinase for the first time.
GO:0004674 protein serine/threonine kinase activity	IEA GO_REF:0000003	ACCEPT	Summary: Electronic EC-based annotation of Ser/Thr protein kinase activity; correct and a core molecular function of BIK1. Reason: BIK1 is an experimentally validated Ser/Thr protein kinase (EC 2.7.11.1) that phosphorylates RBOHD, OSCA1.3, FLS2, BAK1 and WRKY transcription factors. The electronic EC mapping correctly captures the core catalytic function. Supporting Evidence: PMID:32846426 This phosphorylation is dependent on BIK1 kinase activity, since a kinase-dead variant, GST–BIK1(KD), did not phosphorylate OSCA1.3-loop1
GO:0005524 ATP binding	IEA GO_REF:0000002	ACCEPT	Summary: ATP binding is required for BIK1 kinase catalysis; supported by a defined ATP-binding site and an ATP-binding Lys-105 whose mutation abolishes activity. Reason: BIK1 has a canonical protein kinase ATP-binding pocket (Gly-rich loop 73-81, catalytic Lys-105). Mutation of Lys-105 (with Lys-106) gives a kinase-dead enzyme, confirming functional ATP binding. Standard supporting MF for an active kinase. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md ATP-binding Lys-105; active-site (proton acceptor) Asp-202.
GO:0005634 nucleus	IEA GO_REF:0000044	ACCEPT	Summary: Nuclear localization is supported by a focused study showing activation-dependent relocation of BIK1 to the nucleus; this electronic subcellular-location annotation is corroborated experimentally. Reason: A pool of phosphorylated/activated BIK1 moves to the nucleus and phosphorylates WRKY transcription factors. Although BIK1 is predominantly plasma membrane-anchored, nuclear localization is a genuine, mechanistically defined secondary location. Supporting Evidence: PMID:29649442 BIK1 also localizes to the nucleus and interacts directly with WRKY transcription factors involved in the JA and salicylic acid (SA) regulation.
GO:0005886 plasma membrane	IEA GO_REF:0000044	ACCEPT	Summary: Plasma membrane is the principal location of BIK1; this electronic annotation is strongly supported by lipid-anchoring and multiple focused studies. Reason: BIK1 is myristoylated (Gly-2) and palmitoylated (Cys-4) and resides at the plasma membrane where it associates with PRR complexes. Core location for its immune signaling function. Supporting Evidence: PMID:16339855 BIK1 is membrane-localized, suggesting possible involvement in early stages of the recognition or transduction of pathogen response.
GO:0010008 endosome membrane	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: BIK1 is internalized into endocytic compartments after ligand-induced monoubiquitination; endosome membrane localization is experimentally supported. Reason: Endosomal localization reflects ligand-induced internalization of BIK1 with FLS2, a regulated trafficking step downstream of activation rather than the primary site of catalytic immune signaling. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md supported by ligand-induced internalization study
GO:0106310 protein serine kinase activity	IEA GO_REF:0000116	ACCEPT	Summary: Rhea/EC-based electronic annotation of protein serine kinase activity; consistent with experimentally proven BIK1 catalytic activity. Reason: BIK1 phosphorylates serine residues on substrates such as RBOHD (S39/S339/ S343) and OSCA1.3 (S54). The electronic annotation correctly captures part of the core kinase activity; it is independently supported by EXP annotations. Supporting Evidence: PMID:32846426 BIK1 predominantly phosphorylates S54
GO:0005515 protein binding	IPI PMID:20018686 A receptor-like cytoplasmic kinase, BIK1, associates with a ...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from the BIK1-FLS2/BAK1 interaction study; uninformative as a molecular function although the interaction itself is real and central. Reason: Per curation guidelines, bare GO:0005515 protein binding is uninformative. The underlying interaction (BIK1 associating with and trans-phosphorylating the FLS2/BAK1 receptor complex) is genuine and is captured by the kinase activity MF and the PRR signaling BP terms; the bare binding term should not be treated as a core function. Supporting Evidence: PMID:20018686 BIK1 associates with FLS2 and BAK1 in vivo and in vitro. BIK1 is phosphorylated by BAK1, and BIK1 also directly phosphorylates BAK1 and FLS2 in vitro.
GO:0004674 protein serine/threonine kinase activity	TAS PMID:30584105 Conserved fungal effector suppresses PAMP-triggered immunity...	ACCEPT	Summary: Traceable assertion of Ser/Thr protein kinase activity; correct and a core molecular function of BIK1. Reason: BIK1 is an experimentally validated Ser/Thr protein kinase. This is one of several annotations capturing the core catalytic function and is well supported. Supporting Evidence: PMID:24104392 Arabidopsis BOTRYTIS-INDUCED KINASE1 (BIK1) is a receptor-like cytoplasmic kinase acting early in multiple signaling pathways important for plant growth and innate immunity. file:ARATH/BIK1/BIK1-deep-research-falcon.md Experimental data support BIK1 as an active serine/threonine protein kinase
GO:0005886 plasma membrane	EXP PMID:26021844 Regulatory role of BOTRYTIS INDUCED KINASE1 in ETHYLENE INSE...	ACCEPT	Summary: Experimental support for plasma membrane localization via myristoylation at Gly-2; core location. Reason: This study mapped N-myristoylation at Gly-2 and showed that Gly-2 mutation drastically reduces plasma membrane localization, directly demonstrating lipid-anchored PM residence. Core to BIK1 function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md Drastic reduction of plasma membrane localization and strong increase of cytoplasmic localization.
GO:0005886 plasma membrane	EXP PMID:32404997 Ligand-induced monoubiquitination of BIK1 regulates plant im...	ACCEPT	Summary: Experimental support for plasma membrane localization where BIK1 resides with FLS2 before ligand-induced internalization; core location. Reason: BIK1 is monoubiquitinated and internalized from the plasma membrane upon flg22 perception, establishing the PM as the resting site of BIK1 within the receptor complex. Core location. Supporting Evidence: PMID:32404997 Ligand-induced monoubiquitination of BIK1 regulates plant immunity.
GO:0010008 endosome membrane	EXP PMID:32404997 Ligand-induced monoubiquitination of BIK1 regulates plant im...	KEEP AS NON CORE	Summary: Experimentally supported endosome membrane localization following ligand-induced internalization; a regulated downstream trafficking step. Reason: BIK1 internalizes into endocytic compartments after monoubiquitination upon flg22 perception. Real but a downstream regulatory localization, not the primary site of signaling activity. Supporting Evidence: PMID:32404997 Ligand-induced monoubiquitination of BIK1 regulates plant immunity.
GO:0106310 protein serine kinase activity	EXP PMID:24104392 Identification and functional analysis of phosphorylation re...	ACCEPT	Summary: Experimentally demonstrated protein serine kinase activity (and dual-specificity autophosphorylation); core molecular function. Reason: This study profiled BIK1 autophosphorylation, demonstrating serine phosphorylation activity and establishing BIK1 as a dual-specificity kinase. Core catalytic function. Supporting Evidence: PMID:24104392 we identified nineteen in vitro autophosphorylation sites of BIK1 including three phosphotyrosine sites, thereby proving BIK1 is a dual-specificity kinase for the first time.
GO:0106310 protein serine kinase activity	EXP PMID:32846426 The calcium-permeable channel OSCA1.3 regulates plant stomat...	ACCEPT	Summary: Experimentally demonstrated serine kinase activity toward OSCA1.3 (S54); core molecular function. Reason: BIK1 directly phosphorylates the OSCA1.3 channel at Ser-54 in a kinase-activity-dependent manner, directly demonstrating protein serine kinase activity on a physiological substrate. Core catalytic function. Supporting Evidence: PMID:32846426 BIK1 predominantly phosphorylates S54
GO:0005515 protein binding	IPI PMID:31803215 BIK1 and ERECTA Play Opposing Roles in Both Leaf and Inflore...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from the BIK1-ERECTA developmental study; uninformative MF although the interaction (and phosphorylation of ER) is real. Reason: Bare GO:0005515 is uninformative. The specific relationship (BIK1 interacts with and phosphorylates ERECTA-family RLKs in leaf/inflorescence development) is a genuine kinase-substrate interaction captured by the kinase MF; the bare binding term is not a core function. Supporting Evidence: PMID:31803215 BIK1 interacts with ER-family proteins and directly phosphorylates ER.
GO:0005634 nucleus	HDA PMID:15610358 High-throughput protein localization in Arabidopsis using Ag...	ACCEPT	Summary: Nucleus from a generic high-throughput GFP-ORF screen; the location is independently corroborated by a focused activation-dependent study so it is accepted. Reason: Although this HDA call comes from a generic GFP-ORF overexpression localization screen rather than a focused BIK1 study, nuclear localization is independently and directly demonstrated (PMID:29649442) as a regulated, activation-dependent location where BIK1 phosphorylates WRKY TFs. Supporting Evidence: PMID:29649442 BIK1 also localizes to the nucleus and interacts directly with WRKY transcription factors
GO:0005730 nucleolus	HDA PMID:15610358 High-throughput protein localization in Arabidopsis using Ag...	MARK AS OVER ANNOTATED	Summary: Nucleolar localization derives only from a generic GFP-ORF overexpression screen and is not substantiated by any focused BIK1 study; likely an over-annotation. Reason: The nucleolus call comes from a high-throughput GFP-ORF transient overexpression screen that classified proteins into broad categories including nucleolar. It is biologically implausible for a myristoylated/palmitoylated, membrane-anchored immune kinase and is not corroborated by any dedicated BIK1 study (focused work supports plasma membrane, nucleus and endosomes only). Supporting Evidence: PMID:15610358 These patterns have been classified into five main categories, including cytoplasmic, nuclear, nucleolar, organellar and endomembrane compartments.
GO:0005737 cytoplasm	HDA PMID:15610358 High-throughput protein localization in Arabidopsis using Ag...	KEEP AS NON CORE	Summary: Cytoplasm from a generic GFP-ORF overexpression screen; weakly supported and likely an artifact of overexpression, kept as non-core. Reason: The cytoplasmic HDA call is from a generic overexpression localization screen. A cytoplasmic pool can appear when membrane targeting (myristoylation/ palmitoylation) is overwhelmed or disrupted (e.g. Gly-2 mutation increases cytoplasmic signal), so it is biologically plausible but not a core functional location; retained as non-core. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md strong increase of cytoplasmic localization
GO:0004674 protein serine/threonine kinase activity	IDA PMID:32846426 The calcium-permeable channel OSCA1.3 regulates plant stomat...	ACCEPT	Summary: Direct experimental demonstration of Ser/Thr protein kinase activity (phosphorylation of OSCA1.3); core molecular function. Reason: In vitro radioactive kinase assays show BIK1 directly phosphorylates OSCA1.3 in a kinase-activity-dependent manner, directly demonstrating the core Ser/Thr kinase function. Supporting Evidence: PMID:32846426 This phosphorylation is dependent on BIK1 kinase activity, since a kinase-dead variant, GST–BIK1(KD), did not phosphorylate OSCA1.3-loop1
GO:0006468 protein phosphorylation	IDA PMID:32846426 The calcium-permeable channel OSCA1.3 regulates plant stomat...	ACCEPT	Summary: Protein phosphorylation as the biological process by which BIK1 transmits immune signals (e.g. phosphorylating OSCA1.3); core activity. Reason: BIK1 transduces immune signals by phosphorylating downstream substrates. The BP term protein phosphorylation correctly captures this; directly supported by OSCA1.3 phosphorylation. Supporting Evidence: PMID:32846426 BIK1 interacts with and phosphorylates the N-terminal cytosolic loop of OSCA1.3 within minutes of treatment with the peptidic PAMP flg22
GO:0010119 regulation of stomatal movement	IGI PMID:32846426 The calcium-permeable channel OSCA1.3 regulates plant stomat...	ACCEPT	Summary: BIK1 controls stomatal closure during immunity via phosphorylation of the OSCA1.3 Ca2+ channel; well-supported regulatory role. Reason: BIK1-mediated phosphorylation of OSCA1.3 is required for flg22-induced stomatal closure (stomatal immunity), and BIK1/RBOHD also controls stomatal movement. A genuine, mechanistically defined role in regulating stomatal movement in the immune context. Supporting Evidence: PMID:32846426 OSCA1.3 and its phosphorylation by BIK1 are critical for stomatal closure during immune signalling file:ARATH/BIK1/BIK1-deep-research-falcon.md BIK1 (with PBL1) is required for MAMP/DAMP-induced calcium elevations, positioning BIK1 in early signaling outputs beyond ROS.
GO:0005515 protein binding	IPI DOI:10.1038/s41586-020-2210-3	MARK AS OVER ANNOTATED	Summary: Bare protein binding from the monoubiquitination study (BIK1 binds FLS2 and the ATL44/ATL45 ubiquitin ligases); uninformative MF. Reason: Bare GO:0005515 is uninformative. The underlying interactions (BIK1 with FLS2 and with the RING E3 ligases ATL44/RHA3A and ATL45/RHA3B) are real and are captured by the PRR signaling and ubiquitination-related biology described in the notes; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md monoubiquitination of BIK1 by ATL44/RHA3A and ATL45/RHA3B
GO:0012505 endomembrane system	IDA DOI:10.1038/s41586-020-2210-3	KEEP AS NON CORE	Summary: Endomembrane system localization reflecting ligand-induced internalization of BIK1; correct but more specific endosome terms are also annotated. Reason: Consistent with BIK1 internalization into endocytic compartments after monoubiquitination. The more specific endosome/endosome membrane terms are also present; this general term is retained as a non-core, downstream trafficking location. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md supported by ligand-induced internalization study
GO:0002221 pattern recognition receptor signaling pathway	IMP DOI:10.1038/s41586-020-2210-3	ACCEPT	Summary: BIK1 is a central component of PRR (FLS2/EFR-BAK1) signaling; core biological process. Reason: BIK1 is the canonical RLCK relaying signaling from cell-surface PRR complexes downstream of PAMP perception. PRR signaling pathway is a core BP for BIK1, supported by loss-of-function phenotypes in immune signaling. Supporting Evidence: PMID:20018686 BIK1 is an essential component in MAMP signal transduction, which links the MAMP receptor complex to downstream intracellular signaling. file:ARATH/BIK1/BIK1-deep-research-falcon.md BIK1 is repeatedly described as a PRR-associated kinase acting downstream of multiple PRRs (FLS2, EFR; also CERK1, PEPR1), linking PAMP perception to downstream defense signaling.
GO:0002237 response to molecule of bacterial origin	IDA DOI:10.1038/s41586-020-2210-3	ACCEPT	Summary: BIK1 mediates responses to bacterial PAMPs such as flagellin (flg22); core immune process. Reason: BIK1 is phosphorylated and monoubiquitinated specifically in response to the bacterial PAMP flg22 and is required for the downstream immune response. The term (which explicitly covers flagellin-derived peptides) is a core BP for BIK1. Supporting Evidence: PMID:20018686 BIK1 that is rapidly phosphorylated upon flagellin perception, depending on both FLS2 and BAK1.
GO:0005768 endosome	IDA DOI:10.1038/s41586-020-2210-3	KEEP AS NON CORE	Summary: Endosome localization from ligand-induced internalization of BIK1; experimentally supported downstream trafficking location. Reason: BIK1 internalizes into endosomes after monoubiquitination upon flg22 perception. A genuine but downstream regulatory localization, not the primary site of signaling activity. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md internalization "into endocytic compartments"
GO:0005886 plasma membrane	IDA DOI:10.1038/s41586-020-2210-3	ACCEPT	Summary: Plasma membrane localization of BIK1 within the FLS2 complex prior to internalization; core location. Reason: BIK1 resides at the plasma membrane in the resting receptor complex and is internalized upon ligand perception, confirming the PM as its primary functional location. Core. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md Plasma membrane is the principal, well-supported location
GO:0042742 defense response to bacterium	IMP DOI:10.1038/s41586-020-2210-3	ACCEPT	Summary: BIK1 is required for defense against bacterial pathogens (e.g. Pseudomonas syringae); core immune function. Reason: BIK1 ubiquitination mutants show enhanced susceptibility to Pseudomonas syringae pv. tomato DC3000, and BIK1 drives the ROS/Ca2+ outputs that restrict bacterial entry. Defense response to bacterium is a core BP. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md negative regulator of basal resistance to Pst file:ARATH/BIK1/BIK1-deep-research-falcon.md BIK1-dependent signaling through RBOHD is linked to stomatal movement that restricts bacterial entry, with impairment when BIK1 function (or its RBOHD phosphorylation) is compromised.
GO:0050832 defense response to fungus	IMP DOI:10.1038/s41586-020-2210-3	ACCEPT	Summary: BIK1 contributes to defense against fungal pathogens (e.g. Botrytis cinerea); supported immune function. Reason: BIK1 was originally identified as required for resistance to necrotrophic fungi, and ubiquitination mutants show enhanced susceptibility to Botrytis cinerea. Defense response to fungus is a genuine, core-adjacent immune BP. Supporting Evidence: PMID:16339855 Inactivation of BIK1 causes severe susceptibility to necrotrophic fungal pathogens
GO:0005634 nucleus	IDA PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	ACCEPT	Summary: Direct experimental evidence that activated BIK1 localizes to the nucleus to phosphorylate WRKY TFs; mechanistically defined secondary location. Reason: This focused study directly demonstrated nuclear localization of BIK1 and its interaction with nuclear WRKY transcription factors regulating JA/SA. A genuine activation-dependent location supporting the PRR-BIK1-WRKY axis. Supporting Evidence: PMID:29649442 BIK1 also localizes to the nucleus and interacts directly with WRKY transcription factors involved in the JA and salicylic acid (SA) regulation.
GO:0005886 plasma membrane	IDA PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	ACCEPT	Summary: Direct experimental confirmation of plasma membrane localization (the documented resting location of BIK1); core location. Reason: This study confirms BIK1's documented plasma membrane localization alongside its activation-dependent nuclear pool. PM is the core functional location. Supporting Evidence: PMID:29649442 in addition to its documented plasma membrane localization, BIK1 also localizes to the nucleus
GO:0080141 regulation of jasmonic acid biosynthetic process	IEP PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	KEEP AS NON CORE	Summary: BIK1 regulates JA levels via phosphorylation of WRKY TFs; a downstream regulatory output rather than the core biochemical function. Reason: BIK1 modulates JA homeostasis through the PRR-BIK1-WRKY axis. This is a genuine but downstream/regulatory consequence of BIK1 immune signaling, not its core kinase function; retained as non-core. Supporting Evidence: PMID:29649442 EFR regulates the phytohormone jasmonic acid (JA) through direct phosphorylation of a receptor-like cytoplasmic kinase, BIK1.
GO:0080141 regulation of jasmonic acid biosynthetic process	IMP PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	KEEP AS NON CORE	Summary: BIK1 phosphosite mutants alter JA levels, supporting a regulatory role in JA biosynthesis; downstream output, non-core. Reason: Phosphomimetic mutations at EFR-targeted BIK1 sites elevate JA, genetically linking BIK1 to JA regulation. Genuine but a downstream regulatory output of BIK1 signaling, not its core function. Supporting Evidence: PMID:29649442 Phosphomimetic mutations of these sites resulted in increased phytohormones and enhanced resistance to bacterial infections.
GO:0080142 regulation of salicylic acid biosynthetic process	IEP PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	KEEP AS NON CORE	Summary: BIK1 regulates SA homeostasis via the PRR-BIK1-WRKY axis; downstream regulatory output, non-core. Reason: BIK1 modulates SA levels through phosphorylation of WRKY transcription factors. A genuine downstream regulatory consequence of BIK1 signaling, retained as non-core. (BIK1 was also originally shown to influence SA accumulation.) Supporting Evidence: PMID:29649442 WRKY transcription factors involved in the JA and salicylic acid (SA) regulation
GO:0080142 regulation of salicylic acid biosynthetic process	IMP PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	KEEP AS NON CORE	Summary: BIK1 phosphosite mutants alter SA-associated defense outputs; downstream regulatory role, non-core. Reason: Mutations at EFR-targeted BIK1 phosphosites change hormone levels and bacterial resistance, genetically linking BIK1 to SA regulation. Downstream output of BIK1 signaling, retained as non-core. Supporting Evidence: PMID:29649442 Phosphomimetic mutations of these sites resulted in increased phytohormones and enhanced resistance to bacterial infections.
GO:0002237 response to molecule of bacterial origin	IMP PMID:25522736 Microbe-associated molecular pattern-induced calcium signali...	ACCEPT	Summary: BIK1 is required for calcium responses to bacterial PAMPs (flg22, elf18); core immune process. Reason: BIK1 (with PBL1) is genetically required for MAMP/DAMP-induced calcium elevations triggered by bacteria-derived flg22 and elf18. Core response to bacterial molecules. Supporting Evidence: PMID:25522736 is also required for MAMP/DAMP-induced calcium elevations.
GO:0002237 response to molecule of bacterial origin	IMP PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	ACCEPT	Summary: BIK1 mediates responses to bacterial PAMPs downstream of EFR/FLS2; core immune process. Reason: BIK1 is phosphorylated by the PRR EFR upon perception of bacterial elf18 and is required for elf18/flg22-triggered responses. Core response to bacterial molecules. Supporting Evidence: PMID:29649442 EFR regulates the phytohormone jasmonic acid (JA) through direct phosphorylation of a receptor-like cytoplasmic kinase, BIK1.
GO:0005515 protein binding	IPI PMID:29649442 The Receptor-like Cytoplasmic Kinase BIK1 Localizes to the N...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-EFR and BIK1-WRKY interaction study; uninformative MF although the interactions are biologically central. Reason: Bare GO:0005515 is uninformative. The underlying interactions (BIK1 with the PRR EFR and with nuclear WRKY transcription factors WRKY33/50/51/57) are real and are captured by the kinase MF and the nuclear hormone-regulation BP terms; bare binding is not a core function. Supporting Evidence: PMID:29649442 BIK1 also localizes to the nucleus and interacts directly with WRKY transcription factors
GO:1900424 regulation of defense response to bacterium	IMP PMID:25522736 Microbe-associated molecular pattern-induced calcium signali...	ACCEPT	Summary: BIK1 regulates antibacterial defense via control of early MAMP-induced calcium signaling; supported immune function. Reason: BIK1 is required for MAMP/DAMP-induced calcium signaling that initiates antibacterial defense responses, placing it as a regulator of defense response to bacterium. Core-adjacent immune BP. Supporting Evidence: PMID:25522736 is also required for MAMP/DAMP-induced calcium elevations.
GO:0005794 Golgi apparatus	HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati...	MARK AS OVER ANNOTATED	Summary: Golgi localization derives only from a global membrane-protein correlation-profiling proteomics survey, not a focused BIK1 study; likely over-annotation. Reason: This HDA call is from a high-throughput protein correlation profiling proteomics study of membrane-protein oligomerization, not a dedicated BIK1 localization study. Golgi residence is not supported by any focused BIK1 work (which establishes plasma membrane, nucleus and endosomes), and likely reflects fractionation/co-migration rather than genuine steady-state Golgi localization. Supporting Evidence: PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerization Using Protein Correlation Profiling.
GO:0002221 pattern recognition receptor signaling pathway	IMP PMID:21862710 Biochemical and genetic requirements for function of the imm...	ACCEPT	Summary: BIK1 is genetically and biochemically required for PAMP-triggered immunity downstream of PRRs; core biological process. Reason: This study established biochemical/genetic requirements for BIK1 in PAMP-triggered immunity (and growth/ethylene signaling). PRR signaling pathway is a core BP for BIK1. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md Central RLCK that relays PTI signaling from PRR–BAK1 complexes
GO:0005739 mitochondrion	ISM GO_REF:0000122	REMOVE	Summary: Mitochondrial localization is a pure sequence-model prediction (AtSubP) with no experimental support and is contradicted by BIK1 biology. Reason: This is an ISM (sequence-model) prediction from AtSubP (GO_REF:0000122) with no experimental backing. BIK1 is N-myristoylated/palmitoylated and anchored to the plasma membrane, with experimentally established nucleus and endosome pools; mitochondrial localization is biologically implausible and contradicted by all focused studies. Demonstrably wrong electronic prediction. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md with no experimental support and is inconsistent with the myristoyl/palmitoyl PM anchor
GO:0005515 protein binding	IPI PMID:20404519 Phosphorylation of receptor-like cytoplasmic kinases by bact...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-FLS2/BAK1 interaction and phosphorylation study; uninformative MF although the interaction is central. Reason: Bare GO:0005515 is uninformative. The interaction (BIK1 with FLS2 and BAK1, with mutual trans-phosphorylation) is genuine and captured by the kinase MF and PRR signaling BP; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md FLS2/BAK1 (PMID:20018686, PMID:20404519, PMID:20413097)
GO:0005515 protein binding	IPI PMID:20413097 Receptor-like cytoplasmic kinases integrate signaling from m...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from study showing BIK1 integrates signaling from multiple immune receptors and is an effector target; uninformative MF. Reason: Bare GO:0005515 is uninformative. The biology (BIK1 associating with multiple PRRs and being targeted by a Pseudomonas effector) is captured by the PRR signaling and defense BP terms; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md BIK1 integrates signaling from multiple immune receptors and is targeted by a Pseudomonas effector
GO:0005515 protein binding	IPI PMID:23431184 BIK1 interacts with PEPRs to mediate ethylene-induced immuni...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-PEPR1 interaction study (ethylene-induced immunity); uninformative MF although the interaction is real. Reason: Bare GO:0005515 is uninformative. The specific interaction (BIK1 with the PEPR1 receptor, mediating Pep1/ethylene-induced immunity) is genuine but is better captured by signaling BP terms; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md PEPR1 (PMID:23431184)
GO:0005515 protein binding	IPI PMID:23818580 Inverse modulation of plant immune and brassinosteroid signa...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-BRI1 interaction study (brassinosteroid signaling); uninformative MF although the interaction is real. Reason: Bare GO:0005515 is uninformative. The specific interaction (BIK1 with the BR receptor BRI1, negatively regulating BR signaling) is genuine but better captured by signaling BP terms; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md Negative regulator of brassinosteroid signaling via BRI1 interaction
GO:0005515 protein binding	IPI PMID:24629339 The FLS2-associated kinase BIK1 directly phosphorylates the ...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from the BIK1-RBOHD study; uninformative as bare MF, but the kinase-substrate relationship is a core part of BIK1 function. Reason: Bare GO:0005515 is uninformative. The underlying interaction (BIK1 binding and directly phosphorylating the NADPH oxidase RBOHD to drive the ROS burst) is a core function captured by the kinase MF and ROS/defense BP terms; bare binding should not stand as a separate functional claim. Supporting Evidence: PMID:24629339 directly phosphorylates the NADPH oxidase RbohD at specific sites in a calcium-independent manner to enhance ROS generation.
GO:0005515 protein binding	IPI PMID:25525792 The calcium-dependent protein kinase CPK28 buffers plant imm...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-CPK28 interaction study (regulation of BIK1 turnover); uninformative MF although the interaction is real. Reason: Bare GO:0005515 is uninformative. The specific interaction (CPK28 binding BIK1 to buffer immunity and regulate BIK1 turnover) is a genuine regulatory relationship better described by the regulation biology; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md CPK28 (PMID:25525792)
GO:0005515 protein binding	IPI PMID:27494702 The Arabidopsis Protein Phosphatase PP2C38 Negatively Regula...	MARK AS OVER ANNOTATED	Summary: Bare protein binding from BIK1-PP2C38 interaction study (negative regulation of BIK1); uninformative MF although the interaction is real. Reason: Bare GO:0005515 is uninformative. The specific interaction (the phosphatase PP2C38 binding and negatively regulating BIK1 activation) is a genuine regulatory relationship; bare binding is not a core function. Supporting Evidence: file:ARATH/BIK1/BIK1-notes.md PP2C38 (PMID:27494702)
GO:0005886 plasma membrane	IDA PMID:16339855 The membrane-anchored BOTRYTIS-INDUCED KINASE1 plays distinc...	ACCEPT	Summary: Original demonstration that BIK1 is membrane-localized; core location. Reason: The founding BIK1 study showed membrane localization, consistent with its lipid anchoring and role in early pathogen signal transduction. Core location. Supporting Evidence: PMID:16339855 BIK1 is membrane-localized, suggesting possible involvement in early stages of the recognition or transduction of pathogen response.
GO:0009620 response to fungus	IEP PMID:16339855 The membrane-anchored BOTRYTIS-INDUCED KINASE1 plays distinc...	KEEP AS NON CORE	Summary: BIK1 transcript is induced by Botrytis infection; expression-based response to fungus, kept as non-core relative to the more specific defense term. Reason: This IEP annotation reflects transcriptional induction of BIK1 by Botrytis cinerea. It is supported but is an expression-based (IEP) inference; the more specific defense response to fungus (IMP) better captures the functional role. Supporting Evidence: PMID:16339855 the Arabidopsis thaliana BOTRYTIS-INDUCED KINASE1 (BIK1) gene that is transcriptionally regulated by Botrytis cinerea infection.
GO:0016301 kinase activity	IDA PMID:16339855 The membrane-anchored BOTRYTIS-INDUCED KINASE1 plays distinc...	MODIFY	Summary: General kinase activity; correct but less specific than the proven protein Ser/Thr kinase activity. Reason: BIK1 is a protein Ser/Thr (dual-specificity) kinase. The generic kinase activity term should be replaced by the specific protein serine/threonine kinase activity term, which is independently and experimentally supported. Proposed replacements: protein serine/threonine kinase activity Supporting Evidence: PMID:16339855 BIK1 encodes a regulatory protein, specifically a protein kinase, predicted to be specific to Ser/Thr residues
GO:0046777 protein autophosphorylation	IDA PMID:16339855 The membrane-anchored BOTRYTIS-INDUCED KINASE1 plays distinc...	KEEP AS NON CORE	Summary: BIK1 autophosphorylates on numerous Ser/Thr/Tyr residues; a real activity but a mechanistic/PTM detail rather than the primary biological role. Reason: Autophosphorylation is experimentally well documented (19 in vitro autophosphorylation sites, including phosphotyrosines) and contributes to BIK1 activation, but it is a self-directed catalytic detail; the core function is trans-phosphorylation of downstream immune substrates. Retained as non-core. Supporting Evidence: PMID:24104392 we identified nineteen in vitro autophosphorylation sites of BIK1 including three phosphotyrosine sites
GO:0050832 defense response to fungus	IMP PMID:16339855 The membrane-anchored BOTRYTIS-INDUCED KINASE1 plays distinc...	ACCEPT	Summary: bik1 mutants are severely susceptible to necrotrophic fungi, establishing a genuine role in defense response to fungus; core-adjacent immune function. Reason: Loss of BIK1 causes severe susceptibility to the necrotrophic fungi Botrytis cinerea and Alternaria brassicicola, directly demonstrating a required role in antifungal defense. Supporting Evidence: PMID:16339855 Inactivation of BIK1 causes severe susceptibility to necrotrophic fungal pathogens

Gene Description

Existing Annotations Review

Core Functions

Acts as a dual-specificity (predominantly Ser/Thr) protein kinase that, upon trans-phosphorylation by BAK1 within ligand-activated PRR complexes, directly phosphorylates downstream immune substrates to relay PAMP-triggered immunity signaling.

Directly phosphorylates the NADPH oxidase RBOHD in a calcium-independent manner to drive the apoplastic reactive oxygen species (ROS) burst that underlies antibacterial immunity and stomatal defense.

Phosphorylates and activates the calcium-permeable channel OSCA1.3 to promote PAMP-induced cytosolic Ca2+ influx and stomatal closure during immune signaling.

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