mouse anti cd71 monoclonal antibody  (Proteintech)

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) SDS-PAGE analysis of maleimide-conjugated HRP-VP1u. (B) Proximity labeling in UT7/Epo cells. HRP-VP1u was bound to cells at 4 °C, followed by pulse labeling. HRP-VP1u and biotinylated proteins were detected using anti-FLAG and anti-biotin antibodies, respectively. A representative confocal image is shown. Scale bar: 10 μm. (C) Mass spectrometry analysis of affinity-purified biotinylated proteins. Proteins identified in three independent experiments were plotted according to log₂ fold change (log2FC) relative to HRP-only controls and protein intensity. Common hits are shown in distinct colors, with TfR1 highlighted. (D) Proteins identified as containing tyramide-modified tyrosine residues in the three independent experiments. TfR1 is highlighted in red and represents the only protein detected in all three experiments.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: SDS Page, Labeling, Mass Spectrometry, Affinity Purification, Modification

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: Confocal microscopy analysis of UT7/Epo cells incubated at 4 °C with recombinant FLAG-tagged VP1u or intact B19V to assess primary surface interactions. Top panels: VP1u (green) and TfR1 (red). Merged images demonstrate substantial colocalization at the cell periphery. Bottom panels: B19V (green) and TfR1 (red). Merged images show distinct spatial distribution with no evident colocalization. Enlarged views highlight the differential overlap patterns. TfR1 was detected using an antibody directed against its cytosolic tail. Recombinant VP1u was detected via its C-terminal FLAG tag, and native B19V was detected using a monoclonal antibody specific for intact capsids (mAb 860-55D). Scale bar: 10 μm.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Confocal Microscopy, Incubation, Recombinant, FLAG-tag

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Confocal microscopy of UT7/Epo cells preincubated with OKT9 or isotype-matched IgG control and exposed to MS2-VP1u-Atto 488 for 30 min at 4 °C (binding) or 37 °C (internalization). Scale bar: 10 μm. (B) Confocal microscopy of cells pretreated with OKT9 or IgG and incubated with B19V. B19V was detected using a monoclonal antibody specific to intact capsids (mAb 860-55D). Scale bar: 10 μm. (C) Quantification of B19V binding at 4 °C measured by qPCR. (D) Quantification of internalized B19V genomes following uptake at 37 °C. Trypsinization was used to remove non-internalized particles. (E) NS1 mRNA levels 24 h post-infection following preincubation with 2 µg OKT9. (F) Dose-dependent inhibition of NS1 mRNA synthesis following preincubation with increasing concentrations of OKT9 (0, 0.2, 0.5, 1, and 2 µg). All results are presented as the mean ± SD of three or more independent experiments. Statistical significance was calculated using two-sided Student’s t-test. ∗∗∗p < 0.001; ∗∗∗∗p < 0.0001; ns, non-significant.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Confocal Microscopy, Control, Binding Assay, Incubation, Infection, Inhibition

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Confocal microscopy of erythroid (Ku812Ep6), and non-erythroid cells (HeLa, Jurkat and HepG2 cells) incubated with recombinant FLAG-tagged VP1u at 4 °C. VP1u was detected with anti-FLAG antibody (green) and TfR1 with an antibody against its cytosolic domain (red). (B) UT7/Epo cells treated with PNGase F, β1-4-galactosidase (β4Gal), neuraminidase (Neu), β-N-acetylglucosaminidase (β-GlcNAcase), or O-glycosidase prior to incubation with recombinant FLAG-tagged VP1u at 4 °C. VP1u binding was assessed by confocal microscopy. DAPI (blue). Scale bar: 10 μm

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Confocal Microscopy, Incubation, Recombinant, Binding Assay

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: Binding of VP1u monomer (A) and dimer (B) to TfR1-Fc was measured by bio-layer interferometry using serial dilutions. TfR-Fc was immobilized on an anti-Fc biosensor surface. VP1u samples were incubated for 300 s, followed by 300 s dissociation phase. (C) Binding kinetics parameters are summarized in the table. Two binding modes, K D 1 and K D 2, were analyzed using a 2:1 heterogeneous ligand model.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Binding Assay, Incubation

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: Schematic representation of the cryo-EM single particle analysis of VP1u-TfR1 complex.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Cryo-EM Sample Prep, Single Particle

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: Schematic representation of the cryo-EM single particle analysis of TfR1.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Cryo-EM Sample Prep, Single Particle

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Cryo-EM 3D reconstruction of TfR1 in complex with recombinant VP1u monomer. One TfR1 monomer is colored to distinguish the apical, protease-like, and helical domains. The two additional densities corresponding to the two bound VP1u molecules are shown in blue and light blue. (B) Atomic model of the TfR1-VP1u RBD complex structure, depicted as a ribbon diagram with cylinders and stubs representing α-helices and β-strands, respectively. (C) De novo model of RBD (residues 8-69) with cryo-EM density, shown as a mesh envelope. (D) The atomic model of the VP1u RBD displayed as a ribbon diagram. The three α-helices are highlighted and labeled.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Cryo-EM Sample Prep, Recombinant, Labeling

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Atomic model of human TfR1 generated from the cryo-EM structure. Domains are colored as in . (B-D) The cryo-EM structure (red) aligned with human TfR1 crystal structure (gray). Sm 3+ ions are shown in light green spheres. Regions highlighted by blue and yellow boxes are zoomed in panels C and D, respectively. (C) Conformational differences in the apical traverse loop (residues Pro 314–Gly 328) and adjacent residues of the helical domain. (D) Conformational variation in the C-terminal residues. (E) Comparison of the TfR1-alone structure (red) with the VP1u-TfR1 complex (blue). (F) Close-up view of the apical loop, showing the conformational change upon RBD binding (gray).

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Generated, Cryo-EM Sample Prep, Comparison, Binding Assay

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Close-up view of the RBD-TfR1 binding interface from . Secondary structure elements of the RBD and TfR1 are labeled. (B and C) Contacting residues between RBD and TfR1 are shown as stick representations with side chains displayed and residues labeled.

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Binding Assay, Labeling

Journal: bioRxiv

Article Title: Transferrin receptor 1 binds human parvovirus B19 VP1u to facilitate entry

doi: 10.64898/2026.03.12.711364

Figure Lengend Snippet: (A) Residues previously examined for their functional roles in VP1u internalization are highlighted. Residues located within the contact interface with TfR1 are colored yellow, whereas those not found at the interface are colored green. (B) Binding sites of the B19V RBD, human ferritin, and canine parvovirus (CPV) are mapped on the surface of human TfR1. Each interaction site is colored according to the key shown at the bottom. Residue numbering of canine TfR was aligned with that of human TfR. Only consistent contacts for CPV is shown .

Article Snippet: UT7/Epo cells were preincubated with 2 μg, unless otherwise indicated, of anti-human TfR1 monoclonal antibody OKT9 (103101-0N; Caprico Biotechnologies, Duluth, MN) or with an isotype-matched mouse IgG control (14-4714-82; Thermo Fisher) for 30 min at 4 °C prior to addition of MS2-VP1u or B19V.

Techniques: Functional Assay, Binding Assay, Residue