Definition of a Protein Complex
A cellular component should include more than one gene product; complexes of one gene product with a cofactor, e.g. heme and chlorophyll, should not be included. Homomultimeric proteins, e.g. the homodimeric alcohol dehydrogenase, may be included as cellular component terms, as should heteromultimeric proteins, e.g. hemoglobin with alpha and beta chains.