KEY RESOURCES TABLE
| REAGENT or RESOURCE | SOURCE | IDENTIFIER |
| Antibodies | ||
| CTL-IgG | Bujotzek et al. 2016 | PDB: 5DMG |
| CD98hc IgG | Yasutomo et al. 2013 | N/A |
| TfR-1 IgG | Kissel et al. 1998 | N/A |
| CTL-IgG/CD98-scFv | This paper | Genbank: OR253074 |
| CTL-IgG/TfR-1-scFv | This paper | Genbank: OR253073 |
| M2 | Dr. Carl Lagenaur | N/A |
| M6 | Dr. Carl Lagenaur | N/A |
| 29D7 | Qian et al. 2006 | N/A |
| TrkB-IgG/CD98-scFv | This Paper | Genbank: OR253075 |
| Goat anti-human IgG AlexaFluor 647 | Jackson ImmunoResearch | Cat#109-605-098 |
| Goat anti-human IgG AlexaFluor 488 | Jackson ImmunoResearch | Cat#109-546-170 |
| R17 | BioLegend | Cat#113802 |
| RL388 | BioLegend | Cat#128202 |
| Mouse anti-rat IgG AlexaFluor 647 | BioLegend | Cat#407511 |
| Anti-human Polyvalent Immunoglobulins (G,A,M) | Millipore Sigma | Cat#I1761 |
| Goat anti-human IgG-peroxidase | Millipore Sigma | Cat#A0170 |
| NeuN Monoclonal Antibody (1B7) | Thermo Fisher Scientific | Cat#MA5–33103 |
| GFAP Polyclonal Antibody | Thermo Fisher Scientific | Cat#PA1–10019 |
| Phospho-AKT1 (Ser473) Monoclonal Antibody | Thermo Fisher Scientific | Cat#44–621G |
| Phospho-ERK1/ERK2 (Thr202. Tyr204) Polyclonal Antibody | Thermo Fisher Scientific | Cat#36–8800 |
| ZO-1 Monoclonal Antibody (ZO1–1A12), AlexaFluor 488 | Thermo Fisher Scientific | Cat#339188 |
| Akt (pan) (11E7) Rabbit mAb | Cell Signaling Technology | Cat#4685 |
| P44/42 MAPK (Erk1/2) Antibody | Cell Signaling Technology | Cat#9102 |
| TrkB (80E3) Rabbit mAb | Cell Signaling Technology | Cat#4603 |
| Phospho-Akt (Ser473) (D9E) Rabbit mAb | Cell Signaling Technology | Cat#4060 |
| Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204) Antibody | Cell Signaling Technology | Cat#9101 |
| Phospho-TrkB (Tyr516) Polyclonal Antibody | Thermo Fisher Scientific | Cat#PA5–36695 |
| Anti-rabbit IgG HRP-linked Antibody | Cell Signaling Technology | Cat#7074 |
| Bacterial and virus strains | ||
| DH5α | Thermo Fisher Scientific | Cat#18265017 |
| Biological samples | ||
| None | ||
| Chemicals, peptides, and recombinant proteins | ||
| DMEM media | Corning | Cat#10-013-CV |
| BSA | Thermo Fisher Scientific | Cat#BP9706–100 |
| 0.25% trypsin-EDTA | Gibco | Cat#25200056 |
| Antibiotic-antimycotic | Gibco | Cat#15240062 |
| FBS | Corning | Cat#35-010-CV |
| RPMI media | Corning | Cat#10-040-CV |
| Lipofectamine 2000 | Invitrogen | Cat#11668–027 |
| EcoRI-HF | New England Biolabs | Cat#R3101L |
| XbaI | New England Biolabs | Cat#R0145S |
| Q5 High-Fidelity DNA Polymerase | New England Biolabs | Cat#M0491L |
| NheI-HF | New England Biolabs | Cat#R3131L |
| HindIII-HF | New England Biolabs | Cat#R3104L |
| Quick CIP calf intestinal alkaline phosphatase | New England Biolabs | Cat#M0525L |
| T4 ligase | New England Biolabs | Cat#M0202L |
| F17 media | Thermo Fisher Scientific | Cat#A1383502 |
| Glutamine | Invitrogen | Cat#25030081 |
| Kolliphor | Thermo Fisher Scientific | Cat#NC0917244 |
| G418 | Thermo Fisher Scientific | Cat#10131035 |
| Yeastolate | BD Sciences | Cat#292804 |
| Streptavidin AlexaFluor 647 | Invitrogen | Cat#S32357 |
| Imidazole | ACROS Organics | Cat#12202–5000 |
| Mouse TfR | ACRO Biosystems | Cat#TFR-M524b |
| [125I]NaI | Perkin Elmer | Cat#NEZ033A |
| Pierce iodination reagent | Thermo Fisher Scientific | Cat#28601 |
| Phusion HF PCR MasterMix w/ HF Buffer | New England Biolabs | Cat#M0531S |
| Methanol | Thermo Fisher Scientific | Cat#A421–4 |
| Sodium acetate | Sigma-Aldrich | Cat#S2889–250G |
| Isoflurane | Henry Schein | Cat#66794-017-25 |
| Trypan blue | Gibco | Cat#15250061 |
| Krebs buffer | Thermo Fisher Scientific | Cat#J67591.AP |
| Dextran | Acros | Cat#406271000 |
| RIPA buffer | Thermo Fisher Scientific | Cat#WK333492 |
| 100X Halt Protease Inhibitors | Thermo Fisher Scientific | Cat#1860932 |
| Goat serum | Novus Biologicals | Cat#S13150NOV |
| Tween 20 | Thermo Fisher Scientific | Cat#J20605-AP |
| TMB substrate solution | Thermo Fisher Scientific | Cat#N301 |
| H2SO4 | Thermo Fisher Scientific | Cat#A300–212 |
| Sodium bicarbonate | Sigma-Aldrich | Cat#S6297–250G |
| 4% paraformaldehyde | Thermo Fisher Scientifice | Cat#J19943.K2 |
| Sucrose | Thermo Fisher Scientific | Cat#S5–500 |
| OCT | Thermo Fisher Scientific | Cat#4585 |
| Sodium citrate buffer | Thermo Fisher Scientific | Cat#S279–3 |
| 0.5% Triton-X 100 | Alfa Aesar | Cat#A16046 |
| DAPI | Thermo Fisher Scientific | Cat#YC3861511 |
| Anti-fade reagent | Thermo Fisher Scientific | Cat#P36930 |
| Dry milk | Kroger | N/A |
| Phosphatase and protease inhibitor cocktail 100X | Thermo Fisher Scientific | Cat#P178440 |
| 20% SDS | Dot Scientific Inc. | Cat#DSL23100–500 |
| Trizma base | Sigma-Aldrich | Cat#T1503–1KG |
| HCl | Thermo Fisher Scientific | Cat#SA56–4 |
| β-mercaptoethanol | ACROS Organics | Cat#125472500 |
| Glycerol | Thermo Fisher Scientific | Cat#BP229–1 |
| EDTA | Thermo Fisher Scientific | Cat#O2793–500 |
| Bromophenol blue | Thermo Fisher Scientific | Cat#A18469.09 |
| SignalFire ECL Reagent | Cell Signaling Technology | Cat#6883 |
| Critical commercial assays | ||
| Pierce BCA Protein Assay Kit | Thermo Fisher Scientific | Cat#23227 |
| Deposited data | ||
| Antibody Sequences | GenBank | OR253073–5 |
| Experimental models: Cell lines | ||
| Human: HEK293–6E | National Research Council (NRC) of Canada | N/A |
| Human: REN-CD98hc | This paper | N/A |
| Human: REN-TfR | This paper | N/A |
| Human: REN-mTrkB | This paper | N/A |
| Mouse: bEnd.3 | ATCC | Cat#CRL-2299 |
| Experimental models: Organisms/strains | ||
| C57BL/6J mice | Jackson Laboratory | Strain#000664 |
| Oligonucleotides | ||
| None | ||
| Recombinant DNA | ||
| None | ||
| Software and algorithms | ||
| Prism 9.5.1 | GraphPad | https://www.graphpad.com/updates/prism-951-release-notes |
| Python 3.11.5 | Python Software Foundation | https://www.python.org |
| Data fitting algorithm | This Paper | DOI: 10.5281/zenodo.8317352 |
| Other | ||
| Streptavidin MicroBeads | Miltenyi Biotec | Cat#130-048-101 |
| Streptavidin Dynabeads | Invitrogen | Cat#11047 |
| Protein A magnetic beads | Invitrogen | Cat#88846 |
| QIAquick Gel Extraction Kit | Qiagen | Cat#28704 |
| QIAquick PCR Purification Kit | Qiagen | Cat#28104 |
| QIAprep Spin Miniprep Kit | Qiagen | Cat#27106 |
| Protein A Agarose | Thermo Fisher Scientific | Cat#20333 |
| Centrifuge columns | Thermo Fisher Scientific | Cat#89898 |
| Zeba Spin Desalting Columns | Thermo Fisher Scientific | Cat#89894; Cat#89892; Cat#89890 |
| Invitrogen NuPAGE 10% Bis-Tris, 1.0 mm, Midi Protein GEL (SDS-PAGE) | Thermo Fisher Scientific | Cat#WG1203BOX |
| Superdex 200 Increase 10/300 GL column | GE | Cat#28990944 |
| 96-well plates | VWR | Cat#650261 |
| Protein A Dynabeads | Invitrogen | Cat#10002D |
| Ni-NTA agarose | Qiagen | Cat#30230 |
| Heparin-coated capillary tubes | Thermo Fisher Scientific | Cat#22–3652566 |
| TissueLyser LT | Qiagen | Cat#85600 |
| Immulon 4HBX flat bottom plates | Thermo Fisher Scientific | Cat#3855 |
| 30kDa MW centrifugal filter | Millipore Sigma | Cat#UFC503096 |
| IVIS Lumina S5 | Perkin Elmer | |
| Cryostat | Leica | Cat#NX50 |
| Glass slides | Thermo Fisher Scientific | Cat#1255015 |
| Hydrophobic pen | Vector Laboratories | Cat#H-4000 |
| Coverslip | Thermo Fisher Scientific | Cat#12543D |
| Confocal microscope | Nikon | A1si |
| Flow cytometer, ZE5 cell analyzer | Bio-Rad | Cat#12004278 |
| 6-well plates | Thermo Fisher Scientific | Cat#140675 |
| TLC silica gel 60F254 plates | Millipore Sigma | Cat#105554 |
| 4–12% Bis-Tris SDS-PAGE gel | Thermo Fisher Scientific | Cat#WG1401A |
| MagicMark XP western Protein Standard | Thermo Fisher Scientific | Cat#LC5602 |
| Nitrocellulose membrane | Thermo Fisher Scientific | Cat#IB23001 |
| iBlot 2 Dry Transfer System | Thermo Fisher Scientific | Cat#IB21001 |