# Protein Pathfinder

> Protein Pathfinder (iPhone/iPad app by Heebok Lee.)

- Source: https://appshunter.io/ios/app/protein-pathfinder/id6757447272 (this page in markdown: same URL + `.md`)
- Developer: [Heebok Lee](https://appshunter.io/developer/1855773499)
- Category: Reference, Books
- Price: Free
- Age rating: 4+
- Requires: iOS 15.6 · 21 MB
- Languages: American English
- Released: 2026-09-27
- Data updated: 2026-09-29
- User reviews in markdown: https://appshunter.io/ios/app/protein-pathfinder/id6757447272/reviews.md

## What is Protein Pathfinder?

Protein Interaction Pathfinder turns two gene names into a fully evidenced, visually explorable interaction pathway — combining STRING network data, structural biology, and expression validation in one research tool.

WHETHER YOU'RE MAPPING A SIGNALING CASCADE, checking whether two proteins can plausibly interact in a specific cell line, or just want to see a protein's real electrostatic surface, this app builds the evidence trail for you instead of leaving you to stitch together five different databases by hand.

KEY FEATURES

Pathway Discovery
• Enter any two human gene symbols and find the shortest interaction path between them
• Choose your evidence type: Functional, Physical, or directional Regulatory (v12 or the v12.5 preview with activation/inhibition signs)
• See the full STRING evidence breakdown for every edge — experimental, curated database, text mining, co-expression, neighborhood, gene fusion, and co-occurrence scores
• Jump straight to the live STRING network graph for any pair

Independent Dual-Panel 3D Structures
• View both proteins' real PDB structures side by side, each with its own camera
• Rotate and zoom each protein independently with a single touch — no more fighting over a shared view
• Overlay phosphorylation sites directly on the 3D surface

Electrostatic Surface Visualization
• Color each protein's surface by charge — red for negative, blue for positive — computed from real CHARMM27 force-field partial charges across nearly every atom, not just a handful of charged residues
• Fine-tune the approximation yourself: histidine protonation state, contrast, Debye screening length, and visual intensity are all adjustable sliders
• A fast, on-device approximation built for exploration — not a substitute for a full Poisson-Boltzmann calculation, and the app is upfront about that distinction

Cell-Type Expression Validation
• Check whether both proteins in an interaction are actually expressed together in a specific cancer cell line (HeLa, MCF-7, MDA-MB-468, A549, and more) or a primary tissue cell type
• Pulls real single-cell and cell-line RNA expression data from the Human Protein Atlas
• Flags subcellular co-localization so you can see whether two co-expressed proteins are even in the same compartment

PhosphoSite Validation
• Cross-reference kinase-substrate relationships against OmniPath and SIGNOR
• See which phosphorylation sites on a substrate are actually documented for a given kinase

Chemical Interaction Context
• Surface known small-molecule / chemical interaction data from STITCH for either protein in your pathway

Built-In Guide
• A full in-app user guide explains every screen, every data source, and every scoring system — no external documentation hunting required

WHY IT'S DIFFERENT

Most interaction-mapping tools stop at "these two proteins are connected." Protein Interaction Pathfinder asks the next three questions automatically: What kind of evidence supports that connection? Would these two proteins ever actually meet inside a real cell? And what does their physical interface actually look like? Answering all three normally means juggling STRING, the PDB, and the Human Protein Atlas in separate browser tabs — this app does it in one pass, on your phone.

DATA SOURCES

All data is pulled live from established, citable public resources: STRING (protein interaction evidence), RCSB PDB (3D structures), the Human Protein Atlas (expression data), OmniPath and SIGNOR (phosphorylation evidence), and STITCH (chemical interactions). Nothing is scraped or pre-baked — every query reflects the current state of these databases.

WHO IT'S FOR

Built for structural and cancer biologists, phosphoproteomics researchers, bioinformatics students, and anyone who needs a fast, evidence-backed answer to "how — and where — do these two proteins actually interact?"

Authors: Heebok Lee, Ph.D. and Gihoon Lee, Ph.D. — offered to the research community as a courtesy.


## Version history (last 2 releases)

### 4.2.1 — 2026-09-29

What’s New

- Added PDB and AlphaFold DB structure support
- Expanded phosphorylation-site display to multiple PTM sites
- Added electrostatic and hydrophilic/hydrophobic surface views
- Improved surface controls and iPad layout
- Enhanced 3D comparison and sharing features
- Improved surface switching stability and performance

### 4.1.3 — 2026-09-28

No release notes.

## More apps by Heebok Lee

- [Protein Viewer Pro](https://appshunter.io/ios/app/protein-viewer-pro/id6755710571)
- [Protein Music Premium](https://appshunter.io/ios/app/protein-music-premium/id6755744851)
- [Astro Viewer](https://appshunter.io/ios/app/astro-viewer/id6755899238)
- [Fractal Universe](https://appshunter.io/ios/app/fractal-universe/id6757321026)
- [Chem Drug Info](https://appshunter.io/ios/app/chem-drug-info/id6759182499)

All apps by Heebok Lee: https://appshunter.io/developer/1855773499

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-29.*