Look up a protein in UniProtKB by accession (e.g. "P04637", "Q9Y6K9", "P0DTC2"). Returns the entry id, reviewed (Swiss-Prot) flag, recommended + alternative protein names, gene names, organism + taxid, sequence length and molecular weight, the curated function description, subcellular locations, Gene Ontology terms (id + term + aspect: biological_process / molecular_function / cellular_component), PDB structure ids, and keywords. Bioinformatics, structural biology, drug-target research, education. Gene-centric sibling: /api/bio/gene. CC-BY UniProt data.