Protein GRAVY
Grand Average of Hydropathy score for one or more protein sequences
Protein Sequence(s)

Raw sequence or multi-FASTA format. Input limit: 500,000 characters. Only standard amino acid codes (A C D E F G H I K L M N P Q R S T V W Y) are counted.

💡 Quick Summary

Protein GRAVY calculates the Grand Average of Hydropathy (GRAVY) score for one or more protein sequences. Positive values indicate hydrophobic proteins (typical of membrane proteins); negative values indicate hydrophilic proteins (typical of soluble cytoplasmic proteins).

📋 How to Use
  1. Paste one or more protein sequences (raw or FASTA) into the text area. Multiple sequences each need their own FASTA title line.
  2. Click Submit. Results appear in a table showing each sequence name, length, and GRAVY score.
  3. Click Load Example to analyse three sample protein sequences.
  4. Use Copy All to copy the tabular results to your clipboard.
🧮 Formulas & Logic
GRAVY
GRAVY = (Σ hydropathy values for all residues) / sequence length (Kyte & Doolittle, 1982)
📊 Result Interpretation
Positive GRAVY

The protein is predominantly hydrophobic. Values > 0 are common in integral membrane proteins and transmembrane helices.

Negative GRAVY

The protein is predominantly hydrophilic. Values < 0 are common in soluble, cytoplasmic proteins.

Near zero GRAVY

The protein has a roughly balanced hydrophobic/hydrophilic character.

🔬 Applications
  • Quickly screening protein sequences for potential membrane association
  • Comparing hydrophobicity across a panel of protein variants
  • Verifying that a recombinant protein of interest has expected hydrophobic character
  • Teaching hydropathy analysis concepts in biochemistry courses
⚠️ Common Mistakes & Warnings
Non-standard residues are ignored

Only the 20 standard amino acid single-letter codes (A C D E F G H I K L M N P Q R S T V W Y) are counted. All other characters are stripped before calculation.

GRAVY is a bulk average

GRAVY does not indicate whether a protein is membrane-spanning; a positive average can result from a hydrophobic core in a soluble protein. Use in conjunction with secondary structure or transmembrane predictions.

❓ Frequently Asked Questions

What is a "good" or "bad" GRAVY score?
There is no single threshold, but as a rough guide: integral membrane proteins typically have GRAVY values above +0.5; most soluble cytoplasmic proteins fall between −0.5 and −2.0. Values near zero suggest amphipathic character.
Why are some residues ignored?
Characters other than the 20 standard amino acid codes (gaps, stop codons *, ambiguous codes B/Z/X, etc.) are removed before calculation because Kyte & Doolittle (1982) only defined hydropathy values for the standard 20 amino acids.
Can I analyse multiple sequences at once?
Yes. Paste sequences in multi-FASTA format — each sequence must start with a line beginning with ">". If no FASTA header is present, the entire input is treated as one sequence.
Protein GRAVY — logic ported from the Sequence Manipulation Suite (Paul Stothard, University of Alberta). Hydropathy values: Kyte & Doolittle (1982).