NCBI Protein Clusters E-Search

Use this endpoint when you need to programmatically search NCBI's Protein Clusters database and retrieve UIDs for downstream lookups, rather than using the NCBI web interface or building E-utilities requests manually. Ideal for bioinformatics workflows that need to identify protein cluster records by name, gene, or sequence keyword.

• Empty result set when query matches no protein clusters
• Invalid or malformed query string returns an error from NCBI E-utilities
• Rate limiting or timeout if NCBI upstream is slow or unavailable
• Payment failure returns 402 before the request is forwarded
• Ambiguous query terms may return large UID sets without ranking