$npx -y skills add adaptyvbio/protein-design-skills --skill protenixStructure prediction with Protenix, an open AlphaFold3 reproduction. Use this skill when: (1) Predicting complex structures with an AF3-class model, (2) Wanting an open alternative to AF3 alongside Boltz and Chai, (3) Validating designed binder-target complexes. For QC thresholds
| 1 | # Protenix Structure Prediction |
| 2 | |
| 3 | [Protenix](https://github.com/bytedance/Protenix) is ByteDance's open PyTorch |
| 4 | reproduction of AlphaFold3 (Apache 2.0). It is an AF3-class complex predictor, useful |
| 5 | next to `boltz` and `chai` for cross-checking designed complexes. Runnable through |
| 6 | biomodals. |
| 7 | |
| 8 | **Use Protenix-v2 for antibody-antigen complexes.** The v2 model (464M params, April |
| 9 | 2026) adds 9 to 13 percentage points of antibody-antigen accuracy over v1 at the |
| 10 | DockQ > 0.23 threshold and is more sample-efficient (v2 at 5 seeds exceeds v1 at 1000). |
| 11 | Select it with `--model-name protenix-v2`. For general complexes, the v1 base model is |
| 12 | fine. |
| 13 | |
| 14 | ## Prerequisites |
| 15 | |
| 16 | | Requirement | Value | |
| 17 | |-------------|-------| |
| 18 | | Runner | Modal (biomodals) | |
| 19 | | GPU | L40S (default; `GPU` env var) | |
| 20 | | Setup | See [Getting started](../../docs/getting-started.md) | |
| 21 | |
| 22 | ## How to run |
| 23 | |
| 24 | ```bash |
| 25 | git clone https://github.com/hgbrian/biomodals && cd biomodals |
| 26 | |
| 27 | printf '>protein|A\nMAWTPLLLLLLSHCTGSLSQ...\n' > target.faa |
| 28 | |
| 29 | uv run --with modal modal run modal_protenix.py \ |
| 30 | --input-faa target.faa \ |
| 31 | --seeds 42 \ |
| 32 | --no-use-msa |
| 33 | ``` |
| 34 | |
| 35 | ## Key parameters |
| 36 | |
| 37 | | Parameter | Default | Description | |
| 38 | |-----------|---------|-------------| |
| 39 | | `--input-faa` | one required | FASTA input (or `--input-json`) | |
| 40 | | `--seeds` | `42` | Comma-separated seeds | |
| 41 | | `--use-msa` / `--no-use-msa` | MSA on | Pass `--no-use-msa` for single-sequence | |
| 42 | | `--model-name` | v1 base | Set `protenix-v2` for antibody-antigen complexes | |
| 43 | | `--use-mini` | off | Switch to the smaller `protenix_mini` model | |
| 44 | | `--out-dir` | `./out/protenix` | Output directory | |
| 45 | |
| 46 | ## When to use Protenix vs Boltz vs Chai |
| 47 | |
| 48 | | Need | Tool | |
| 49 | |------|------| |
| 50 | | Affinity head (small molecules) | boltz (Boltz-2) | |
| 51 | | Fastest, ligand support | chai | |
| 52 | | Open AF3 reproduction | protenix (v1 base) | |
| 53 | | Antibody-antigen complexes | protenix-v2 | |
| 54 | |
| 55 | Ranking a shortlist across more than one predictor is more reliable than trusting a |
| 56 | single model. |
| 57 | |
| 58 | ## Troubleshooting |
| 59 | |
| 60 | | Issue | Cause | Fix | |
| 61 | |-------|-------|-----| |
| 62 | | Missing input error | No `--input-faa`/`--input-json` | Provide one | |
| 63 | | Slow run | MSA enabled | Add `--no-use-msa` | |
| 64 | | OOM | Large complex | Use `--use-mini` or a larger GPU | |
| 65 | |
| 66 | --- |
| 67 | |
| 68 | **Next**: Rank with `ipsae`, filter with `protein-qc`. |