BMP2K

BMP2K (BIKE) is a serine-threonine kinase that controls clathrin- and COPII-dependent membrane trafficking and links these functions to viral infection, hematopoietic differentiation, and cell-cycle decisions (PMID:34480404, PMID:32795391). Its core endocytic activity is to phosphorylate the μ subunit of the AP-2 adaptor complex (T156); loss of this activity disrupts clathrin-coated pit morphology and impairs cargo internalization, and BMP2K is recruited to coated pits through an extended C-terminal interaction with AP-2 that also stabilizes the kinase (PMID:34480404). Through AP-2 phosphorylation and through phosphorylation of the cargo adapter CLINT1 (T294), which enables CLINT1 binding to the dengue virus NS3 protein, BMP2K supports both early (post-internalization) and late (assembly/egress) stages of the dengue virus life cycle (PMID:33137362, PMID:35452674). Two splicing isoforms, BMP2K-L and BMP2K-S, both bind SEC16A and act antagonistically on COPII assembly (distribution of SEC16A/SEC24B and abundance of SEC31A), autophagic degradation, and erythroid differentiation (PMID:32795391, PMID:33025853). BMP2K also interacts with CDK2 and, when upregulated, suppresses megakaryocyte polyploidization in favor of mitosis (PMID:32322386). Its predominantly cytoplasmic distribution is enforced by Ser-1010 phosphorylation that suppresses an NLS and by a glutamine-rich region that drives liquid-liquid phase separation (PMID:36739695).

1. 2020 High

   Established BMP2K as a host kinase required for dengue virus infection and identified AP-2 μ-subunit T156 phosphorylation as a contributing mechanism, connecting the kinase to a defined endocytic substrate.

   Evidence Pharmacological inhibition, BIKE overexpression rescue, and antiviral assays in cell and ex vivo systems

   PMID:33137362

   Open questions at the time

   • Did not separate the kinase's direct catalytic contribution from scaffolding at each viral life-cycle stage
   • Late-stage (assembly/egress) substrate not yet identified in this study
2. 2020 High

   Revealed a non-endocytic role by showing the two BMP2K splicing isoforms differentially control SEC16A/COPII secretory assembly, autophagy, and erythroid differentiation, expanding the kinase beyond AP-2/endocytosis.

   Evidence Isoform-specific depletion, SEC16A Co-IP, juxtanuclear localization, and autophagy/differentiation assays in erythroid cells

   PMID:32795391

   Open questions at the time

   • COPII components were not shown to be direct kinase substrates
   • Mechanism by which L and S isoforms exert opposite effects unresolved
3. 2020 Medium

   Linked BMP2K to megakaryocyte cell-fate decisions, showing it interacts with CDK2 and biases cells toward mitosis over polyploidization when upregulated.

   Evidence CDK2 Co-IP, overexpression/knockdown, and cell-cycle/differentiation assays in megakaryoblastic leukemia cells

   PMID:32322386

   Open questions at the time

   • CDK2 not shown to be a phosphorylation substrate
   • Single Co-IP without structural or reciprocal mapping
   • Catalytic dependence of the cell-cycle phenotype untested
4. 2020 Medium

   Reinforced the isoform-specific autophagy mechanism by tying opposing L/S effects to differential SEC16A-dependent COPII assembly and SEC24B regulation.

   Evidence Isoform-specific depletion, autophagy assays, and COPII assembly analysis (confirmatory same-group study)

   PMID:33025853

   Open questions at the time

   • Largely overlapping methods and same group as the primary study
   • Direct causal chain from COPII to autophagy not established
5. 2021 High

   Defined the endocytic mechanism in detail: BMP2K phosphorylates AP-2 in vitro and in vivo, is recruited to coated pits via a C-terminal AP-2 interaction required for its localization and function, and is itself stabilized by AP-2.

   Evidence In vitro kinase assay, loss-of-function, Co-IP/domain mapping, live CCP imaging, cargo internalization, and zebrafish gastrulation phenotype

   PMID:34480404

   Open questions at the time

   • Structural basis of the C-terminus/AP-2 interaction not resolved
   • Mechanism of AP-2-dependent BMP2K stabilization unknown
6. 2022 High

   Identified CLINT1 T294 as a BMP2K substrate whose phosphorylation drives CLINT1 binding to dengue NS3, explaining how the kinase controls a late (assembly/egress) stage of the viral life cycle.

   Evidence Y2H and AP-MS interaction screens, in vitro and in-cell kinase assays, live-cell imaging of co-trafficking, and DENV assembly/egress assays

   PMID:35452674

   Open questions at the time

   • Endogenous host (non-viral) function of CLINT1 phosphorylation not defined
   • Whether CLINT1 phosphorylation intersects the COPII/AP-2 roles untested
7. 2023 Medium

   Explained BMP2K's cytoplasmic distribution by identifying Ser-1010 phosphorylation that suppresses its NLS and a glutamine-rich region driving osmolarity-sensitive liquid-liquid phase separation.

   Evidence Domain deletion, phospho-mimetic/phospho-dead and NLS mutants, live-cell droplet imaging, and osmolarity perturbation

   PMID:36739695

   Open questions at the time

   • Functional consequence of phase separation for kinase activity or trafficking roles untested
   • Kinase responsible for Ser-1010 phosphorylation unknown
   • No independent replication
8. 2025 Low

   Reported a BMP2K::PDGFRA fusion in a myeloid/lymphoid neoplasm with eosinophilia, nominating BMP2K as a fusion partner in this disease context.

   Evidence RNA-seq fusion detection and DNA NGS in a single clinical case

   PMID:41131416

   Open questions at the time

   • No functional characterization of the fusion protein
   • Single case without mechanistic validation
   • Contribution of BMP2K sequence to fusion oncogenicity unknown

• How BMP2K's distinct activities — AP-2/endocytosis, isoform-specific COPII/autophagy, CDK2/cell-cycle, and phase separation — are integrated and selectively engaged in different cell types remains unresolved.
• No unified model linking the endocytic and secretory/autophagy functions
• Whether the catalytic activity is required for all reported roles is untested
• In vivo physiological substrate repertoire beyond AP-2 and CLINT1 unknown