The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
Research plan overview
We verified AFAP1 identity, curated recent (2023–2024) primary literature, and synthesized domain architecture, mechanisms, localization, signaling pathways, physiological roles, disease links, and quantitative data where available. We prioritized human AFAP1 (AFAP-110; UniProt Q8N556) and avoided conflation with AFAP1L1/AFAP1L2 and AFAP1-AS1.
| Aspect | Key details (mechanistic) | Experimental / Model context | Source (DOI URL and year) |
|---|---|---|---|
| Identity & family distinction vs AFAP1L1/AFAP1L2 | AFAP1 (AFAP-110) is the prototypic AFAP family member; AFAP1L1 and AFAP1L2 share high sequence similarity (AFAP1L1 ~71%, AFAP1L2 ~64%) with conserved PH domains but divergent C-terminal motifs that confer distinct interactions. | Sequence comparisons, domain mapping and family phylogeny from thesis/database analyses. | Snyder 2011 — https://doi.org/10.33915/etd.3379 (2011) (snyder2011anewmember pages 26-30, snyder2011anewmember pages 30-34) |
| Domain architecture | Two pleckstrin homology (PH) domains (PH1 binds PKCα), N-terminal proline-rich SH3-binding motifs and SH2-binding motifs, central leucine-zipper/coiled-coil for multimerization, C-terminal actin-binding domain (ABD) with mapped ABD motifs (~residues 593–637). | Epitope mapping, domain deletion constructs, monoclonal antibody mapping, biochemical fractionation. | Qian et al. 1999 — https://doi.org/10.1089/hyb.1999.18.167 (1999); Xiao et al. 2012 — https://doi.org/10.1007/s00018-011-0812-5 (2012) (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4) |
| Actin binding, crosslinking & multimerization | C-terminal ABD mediates F-actin binding; AFAP1 multimerizes (coiled-coil/leucine zipper) enabling actin cross-linking similar to α-actinin; multimerization required for crosslink function and is PKC-regulated. | In vitro actin co-sedimentation, cross-linking assays, FPLC/blue-native PAGE, mutant (Δlzip/ΔABD) phenotypes. | Rubacha 2010 (2010) (no DOI available) ; Qian et al. 1999 — https://doi.org/10.1089/hyb.1999.18.167 (1999); Xiao et al. 2012 — https://doi.org/10.1007/s00018-011-0812-5 (2012) (rubacha2010xb130insilicob pages 24-28, qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4) |
| Src binding & activation; PKC regulation | AFAP1 binds c-Src via proline-rich SH3-binding motifs and can promote Src activation; PKCα binds PH1 and phosphorylates AFAP1 (e.g., Ser277), altering conformation/multimerization and promoting relocalization to podosomes and increased Src activity. | Biochemical binding assays, PKC activation (PMA), phosphorylation mapping, cell imaging of podosome formation; cancer cell lines (MDA-MB-231, PC3). | Snyder 2011 — https://doi.org/10.33915/etd.3379 (2011); Rubacha 2010 (2010); Cunnick et al. 2015 — https://doi.org/10.1038/onc.2014.205 (2015) (snyder2011anewmember pages 30-34, rubacha2010xb130insilicob pages 24-28, cunnick2015actinfilamentassociatedprotein pages 1-3) |
| Subcellular localization | Localizes to F-actin stress fibers and focal adhesions in resting cells; relocates to podosomes/invadopodia and lamellipodia upon PKC/Src activation or transformation; in vivo AFAP1 required for apical localization of active c-Src in lactating mammary epithelium. | Immunofluorescence, fractionation, AFAP1 knockout mice (mammary gland), cancer cell imaging. | Cunnick et al. 2015 — https://doi.org/10.1038/onc.2014.205 (2015); Xiao et al. 2012 — https://doi.org/10.1007/s00018-011-0812-5 (2012) (cunnick2015actinfilamentassociatedprotein pages 1-3, xiao2012theactinbindingdomain pages 2-4) |
| Signaling pathways | Key axes: PKC → AFAP1 → Src (AFAP1 as adaptor/activator of Src); reported role downstream of TGF-β to facilitate Src-dependent CCN2 induction in osteoblast models (AFAP1 required for Src activation in growth factor signaling). | Cell-based signaling assays, primary osteoblasts and siRNA, promoter assays and biochemical readouts of Src/CCN2. | Cunnick et al. 2015 — https://doi.org/10.1038/onc.2014.205 (2015); supporting mechanistic literature and reviews (cunnick2015actinfilamentassociatedprotein pages 1-3, snyder2011anewmember pages 30-34) |
| Physiologic role | Required for proper c-Src activity spatially/temporally during lactation: AFAP1 knockout mice show defective secretory activation (large cytoplasmic lipid droplets), reduced c-Src activity and impaired nursing. | AFAP1-null mouse model, histology, biochemical assays of c-Src activity. | Cunnick et al. 2015 — https://doi.org/10.1038/onc.2014.205 (2015) (cunnick2015actinfilamentassociatedprotein pages 1-3) |
| 2023–2024 development (regulation & antiviral link) | Matsumoto et al. (2023) identified CSNK2B (CK2β) as an IRF1 co-regulator: CSNK2B modulates IRF1 chromatin binding and locus-specific control of AFAP1 transcription; CSNK2B also mediates phosphorylation-dependent activation of AFAP1–Src signaling linked to antiviral effects. | Proteomics, CUT&RUN genome-wide IRF1 binding, phosphorylation assays, antiviral functional assays. | Matsumoto et al. 2023 — https://doi.org/10.1093/nar/gkad298 (2023) (matsumoto2023csnk2bmodulatesirf1 pages 1-2) |
| Disease associations (cancer invasion/metastasis) | AFAP1 promotes cytoskeletal remodeling, invadopodia/podosome formation, adhesion and invasion in cancer cells; AFAP1 expression and function linked experimentally to increased invasive phenotypes and observed upregulation in some tumors (e.g., prostate, breast models). | Cancer cell lines (invasion/matrix degradation assays), xenograft/RNAi studies, database/expression surveys. | Snyder 2011 — https://doi.org/10.33915/etd.3379 (2011); Rubacha 2010 (2010); Qian et al. 1999 — https://doi.org/10.1089/hyb.1999.18.167 (1999) (snyder2011anewmember pages 39-43, rubacha2010xb130insilicob pages 24-28, qian1999monoclonalantibodiesdirected pages 1-5) |
Table: Concise table summarizing AFAP1/AFAP-110 domains, mechanistic functions, localization, signaling roles, physiologic effects and recent (2023) regulatory findings with primary-source DOIs and contextual citations for each entry.
1) Key concepts and definitions with current understanding
- Identity and nomenclature. AFAP1 (actin filament-associated protein 1), also known as AFAP-110, is a human adaptor/scaffold that binds F-actin and regulates Src-family kinase signaling. It is the prototypic member of the AFAP family (AFAP1, AFAP1L1, AFAP1L2). AFAP1 is distinct from AFAP1L1 and AFAP1L2 (XB130/PI3KAP) despite sequence conservation in PH domains; AFAP1 harbors SH3-binding proline-rich motifs that engage Src, a leucine-zipper/coiled-coil for multimerization, and a C-terminal actin-binding domain that mediates actin crosslinking (snyder2011anewmember pages 26-30, snyder2011anewmember pages 30-34, qian1999monoclonalantibodiesdirected pages 1-5).
- Domain architecture. AFAP1 contains two pleckstrin homology (PH) domains (PH1 binds PKCα), multiple SH2- and SH3-binding motifs (including two N‑terminal proline-rich SH3 ligands), a central leucine-zipper/coiled-coil that mediates multimerization and conformational regulation, and a C-terminal actin-binding domain (ABD) with mapped actin-binding sequences around residues ~593–637 (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4, snyder2011anewmember pages 30-34).
- Primary biochemical functions. AFAP1 binds F‑actin directly and forms multimers that crosslink actin filaments; it also binds and can activate c‑Src, positioning AFAP1 as a mechanistic link between the actin cytoskeleton and Src-family kinase signaling (qian1999monoclonalantibodiesdirected pages 1-5, rubacha2010xb130insilicob pages 24-28, snyder2011anewmember pages 30-34).
2) Recent developments and latest research (2023–2024 prioritized)
- CSNK2B–IRF1 regulation of AFAP1 and antiviral signaling (2023). Matsumoto et al. demonstrated that CSNK2B (CK2β) interacts with IRF1 to modulate genome-wide chromatin binding; CSNK2B depletion causes an abnormal accumulation of IRF1 at AFAP1 loci and downregulates AFAP1 transcription. CSNK2B further mediates phosphorylation-dependent activation of AFAP1–Src signaling and contributes to antiviral effects against flaviviruses, identifying AFAP1 as an IRF1/CK2β‑responsive effector that connects cytoskeletal signaling to innate immunity (Nucleic Acids Research, 2023; doi:10.1093/nar/gkad298) (matsumoto2023csnk2bmodulatesirf1 pages 1-2).
- Context from established AFAP1 mechanistic literature supports and frames the 2023 finding: AFAP1’s ability to activate Src and remodel actin provides biological plausibility for antiviral phenotypes when AFAP1–Src signaling is modulated (snyder2011anewmember pages 30-34, rubacha2010xb130insilicob pages 24-28, xiao2012theactinbindingdomain pages 1-2).
3) Current applications and real-world implementations
- Physiological model and in vivo application (mammary gland). AFAP1 knockout in mice revealed a requirement for AFAP1 in secretory activation during lactation: AFAP1 forms a prolactin-induced complex with c‑Src, becomes tyrosine‑phosphorylated, and is necessary for spatial and temporal regulation of c‑Src activity at the apical surface of luminal epithelial cells; AFAP1 loss reduces c‑Src activity and impairs milk production (Oncogene, 2015; doi:10.1038/onc.2014.205) (cunnick2015actinfilamentassociatedprotein pages 1-3).
- Cell biology tools/assays. AFAP1 domain mutants (ΔABD, Δleucine zipper) are used to dissect actin-binding vs. multimerization functions, assess stress fiber formation, focal adhesion maturation, podosome/invadopodia dynamics, and matrix degradation in multiple cell models; these reagents are widely used to probe cytoskeletal signaling and Src activation in vitro (Cell Mol Life Sci, 2012; doi:10.1007/s00018-011-0812-5) (xiao2012theactinbindingdomain pages 2-4).
- Emerging virology application. The 2023 IRF1–CSNK2B study links AFAP1 to host antiviral responses, suggesting AFAP1–Src signaling as a cellular effector that can be leveraged or modulated in antiviral strategies (Nucleic Acids Research, 2023; doi:10.1093/nar/gkad298) (matsumoto2023csnk2bmodulatesirf1 pages 1-2).
4) Expert opinions and analysis from authoritative sources
- AFAP1 as Src activator and actin crosslinker. Foundational analyses describe AFAP1 as a c‑Src activator and actin crosslinking protein that is essential for stress fiber formation and focal adhesion maturation, and that re-localizes to podosomes/invadopodia upon transformation or PKC activation. These mechanistic insights underpin consensus views of AFAP1 as a cytoskeleton–Src adaptor (thesis and review-style syntheses with primary data and citations) (snyder2011anewmember pages 30-34, snyder2011anewmember pages 39-43).
- Domain-function relationships. Detailed mapping shows that PH1 mediates PKCα interaction and phosphorylation (e.g., Ser277), the leucine-zipper/coiled-coil supports multimerization and autoinhibitory contacts, and the C‑terminal ABD is necessary for stable F‑actin association—consistent with an autoinhibited scaffold that is activated by PKC and engages Src (snyder2011anewmember pages 30-34, qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4).
5) Relevant statistics and data from recent studies
- 2023 IRF1–CSNK2B study. Genome-wide CUT&RUN and functional assays showed that CSNK2B depletion produces locus-specific shifts in IRF1 binding with down-regulation of AFAP1 and phosphorylation-dependent activation of AFAP1–Src signaling, contributing to antiviral responses; while the study highlights mechanistic outcomes and specific loci, quantitative parameters most relevant here are the directional regulatory effects at AFAP1 and the functional linkage to antiviral phenotypes (Nucleic Acids Research, 2023; doi:10.1093/nar/gkad298) (matsumoto2023csnk2bmodulatesirf1 pages 1-2).
- In vivo lactation phenotype. AFAP1-null mice demonstrated reduced c‑Src activity during early lactation and loss of apical active c‑Src localization; histology showed large cytoplasmic lipid droplets in alveolar epithelia indicating defective secretory activation (Oncogene, 2015; doi:10.1038/onc.2014.205) (cunnick2015actinfilamentassociatedprotein pages 1-3).
- Actin-binding requirement. Deletion of the ABD shifts AFAP1 from the Triton-insoluble cytoskeletal fraction to the soluble fraction, with concomitant disruption of stress fibers and altered matrix degradation in podosome-like structures, indicating a quantitative redistribution of AFAP1 upon loss of ABD and a functional dependence of cytoskeletal association on the ABD (Cell Mol Life Sci, 2012; doi:10.1007/s00018-011-0812-5) (xiao2012theactinbindingdomain pages 2-4).
Functional role, pathways, and localization
- Primary function. AFAP1 is a modular actin-binding adaptor that crosslinks F‑actin via multimerization and couples cytoskeletal dynamics to Src-family kinase activation. It binds c‑Src through proline-rich SH3 ligands and SH2 motifs and can increase Src activity; PKCα phosphorylates AFAP1 (PH1 interaction), transitioning AFAP1 from an autoinhibited state to an active scaffold that promotes Src activation and cytoskeletal remodeling (qian1999monoclonalantibodiesdirected pages 1-5, snyder2011anewmember pages 30-34, rubacha2010xb130insilicob pages 24-28).
- Localization. AFAP1 localizes to stress fibers and focal adhesions under basal conditions. Upon PKC/Src activation or oncogenic transformation, AFAP1 relocates to podosomes/invadopodia and lamellipodia; in mammary epithelium, AFAP1 is required for the apical localization of active Src during lactation (xiao2012theactinbindingdomain pages 2-4, cunnick2015actinfilamentassociatedprotein pages 1-3, snyder2011anewmember pages 30-34).
- Pathways. Key axes include PKC→AFAP1→Src (PKCα binding to PH1 and Ser277 phosphorylation facilitate Src activation and podosome formation) and TGF‑β→AFAP1→Src→CCN2 induction in osteoblasts (AFAP1 required for Src activation and CCN2 promoter activity in response to TGF‑β) (snyder2011anewmember pages 30-34, cunnick2015actinfilamentassociatedprotein pages 1-3).
Disease and translational relevance
- Cancer cell invasion and adhesion. AFAP1 supports stress fiber formation, focal adhesion maturation, and invadopodia/podosome dynamics. RNAi or loss-of-function reduces adhesion/migration/invasion phenotypes in breast and prostate cancer models, and AFAP1 upregulation has been reported in certain tumors, consistent with a role in invasive behavior (snyder2011anewmember pages 30-34, snyder2011anewmember pages 39-43, rubacha2010xb130insilicob pages 24-28).
- Host defense. 2023 data integrate AFAP1 into IRF1/CK2β‑controlled antiviral signaling, linking a cytoskeletal–Src adaptor to innate immune regulation and suggesting potential for therapeutic modulation (matsumoto2023csnk2bmodulatesirf1 pages 1-2).
Mandatory verification of identity
- Gene symbol and protein description match: AFAP1 encodes actin filament-associated protein 1 (AFAP‑110), as specified; features and functions summarized above align with this identity (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4).
- Organism is human: all core mechanistic evidence cited includes human protein context and mammalian models, consistent with Homo sapiens AFAP1 (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4, cunnick2015actinfilamentassociatedprotein pages 1-3).
- Domains/family alignment: two PH domains, SH3-binding proline-rich motifs, SH2-binding motifs, leucine-zipper/coiled-coil, and C‑terminal ABD are repeatedly validated in the literature for AFAP1 (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4, snyder2011anewmember pages 30-34). We explicitly avoid conflation with AFAP1L1 (cortactin‑interacting) and AFAP1L2/XB130 (PI3KAP), which have overlapping but distinct C‑terminal features (snyder2011anewmember pages 26-30, snyder2011anewmember pages 39-43).
Notes on AFAP1-AS1
- The lncRNA AFAP1‑AS1 is frequently studied in cancer and shows disease associations; however, those statistics and mechanisms correspond to the antisense noncoding RNA, not the AFAP1 protein, and are therefore not used here to infer AFAP1 protein function (xiao2012theactinbindingdomain pages 1-2).
Selected source details with URLs and dates
- Matsumoto et al., 2023, Nucleic Acids Research 51:4451–4466. CSNK2B–IRF1 regulation of AFAP1, antiviral effects; doi:10.1093/nar/gkad298; published April 2023 (matsumoto2023csnk2bmodulatesirf1 pages 1-2).
- Cunnick et al., 2015, Oncogene 34:2640–2649. AFAP1 knockout mouse reveals role in lactation and c‑Src activity/localization; doi:10.1038/onc.2014.205; online May 14, 2015 (cunnick2015actinfilamentassociatedprotein pages 1-3).
- Xiao et al., 2012, Cell Mol Life Sci 69:1137–1151. AFAP ABD requirement for cytoskeletal association and podosome-related function; doi:10.1007/s00018-011-0812-5; October 2012 (xiao2012theactinbindingdomain pages 2-4).
- Qian et al., 1999, Hybridoma 18:167–175. AFAP-110 domain mapping, multimerization, actin binding; doi:10.1089/hyb.1999.18.167; April 1999 (qian1999monoclonalantibodiesdirected pages 1-5).
- Mechanistic syntheses with primary data: Snyder, 2011 (AFAP1 domains, Src activation, PKC regulation, family distinctions), ArXiv DOI 10.33915/etd.3379; 2011 (snyder2011anewmember pages 26-30, snyder2011anewmember pages 30-34, snyder2011anewmember pages 39-43).
Conclusion
Human AFAP1 (AFAP‑110; Q8N556) is a modular adaptor that crosslinks actin and directly regulates Src-family kinase signaling through SH3/SH2 interactions and PKC‑dependent conformational control. It localizes to stress fibers and focal adhesions but redistributes to podosomes/invadopodia under PKC/Src activation, and it is essential for spatial c‑Src activation in lactating mammary epithelium. New 2023 data place AFAP1 under IRF1/CK2β transcriptional and post‑translational control with consequences for antiviral responses, extending AFAP1’s relevance beyond cancer cell motility into innate immunity (qian1999monoclonalantibodiesdirected pages 1-5, xiao2012theactinbindingdomain pages 2-4, cunnick2015actinfilamentassociatedprotein pages 1-3, snyder2011anewmember pages 30-34, matsumoto2023csnk2bmodulatesirf1 pages 1-2).
References
(snyder2011anewmember pages 26-30): Brandi Nicole Snyder. A new member of the afap family, afap1l1, binds to cortactin and localizes to invadosomes. ArXiv, 2011. URL: https://doi.org/10.33915/etd.3379, doi:10.33915/etd.3379. This article has 0 citations.
(snyder2011anewmember pages 30-34): Brandi Nicole Snyder. A new member of the afap family, afap1l1, binds to cortactin and localizes to invadosomes. ArXiv, 2011. URL: https://doi.org/10.33915/etd.3379, doi:10.33915/etd.3379. This article has 0 citations.
(qian1999monoclonalantibodiesdirected pages 1-5): YONG QIAN, ANNE C. GUAPPONE, JOSEPH M. BAISDEN, M. WYNN HILL, JUSTIN M. SUMMY, and DANIEL C. FLYNN. Monoclonal antibodies directed against afap-110 recognize species-specific and conserved epitopes. Hybridoma, 18 2:167-75, Apr 1999. URL: https://doi.org/10.1089/hyb.1999.18.167, doi:10.1089/hyb.1999.18.167. This article has 16 citations.
(xiao2012theactinbindingdomain pages 2-4): Helan Xiao, Bing Han, Monika Lodyga, Xiao-Hui Bai, Yingchun Wang, and Mingyao Liu. The actin-binding domain of actin filament-associated protein (afap) is involved in the regulation of cytoskeletal structure. Cellular and Molecular Life Sciences, 69:1137-1151, Oct 2012. URL: https://doi.org/10.1007/s00018-011-0812-5, doi:10.1007/s00018-011-0812-5. This article has 15 citations and is from a domain leading peer-reviewed journal.
(rubacha2010xb130insilicob pages 24-28): M Rubacha. Xb130: in silico and invivo studies of a novel signal adaptor protein. Unknown journal, 2010.
(cunnick2015actinfilamentassociatedprotein pages 1-3): J. Cunnick, Stephanie Kim, J. Hadsell, S. Collins, C. Cerra, P. Reiser, D. Flynn, and Y. Cho. Actin filament-associated protein 1 is required for csrc activity and secretory activation in the lactating mammary gland. Oncogene, 34:2640-2649, Jul 2015. URL: https://doi.org/10.1038/onc.2014.205, doi:10.1038/onc.2014.205. This article has 16 citations and is from a domain leading peer-reviewed journal.
(matsumoto2023csnk2bmodulatesirf1 pages 1-2): Moe Matsumoto, Jennifer L Modliszewski, Kotomi Shinozaki, Reona Maezawa, Vincent M Perez, Yuki Ishikawa, Ryosuke Suzuki, Kevin L McKnight, Takahiro Masaki, Asuka Hirai-Yuki, Michinori Kohara, Stanley M Lemon, Sara R Selitsky, and Daisuke Yamane. Csnk2b modulates irf1 binding to functional dna elements and promotes basal and agonist-induced antiviral signaling. Nucleic Acids Research, 51:4451-4466, Apr 2023. URL: https://doi.org/10.1093/nar/gkad298, doi:10.1093/nar/gkad298. This article has 5 citations and is from a highest quality peer-reviewed journal.
(snyder2011anewmember pages 39-43): Brandi Nicole Snyder. A new member of the afap family, afap1l1, binds to cortactin and localizes to invadosomes. ArXiv, 2011. URL: https://doi.org/10.33915/etd.3379, doi:10.33915/etd.3379. This article has 0 citations.
(xiao2012theactinbindingdomain pages 1-2): Helan Xiao, Bing Han, Monika Lodyga, Xiao-Hui Bai, Yingchun Wang, and Mingyao Liu. The actin-binding domain of actin filament-associated protein (afap) is involved in the regulation of cytoskeletal structure. Cellular and Molecular Life Sciences, 69:1137-1151, Oct 2012. URL: https://doi.org/10.1007/s00018-011-0812-5, doi:10.1007/s00018-011-0812-5. This article has 15 citations and is from a domain leading peer-reviewed journal.