Table 1.

Summary of UniProt Levels of “Protein Existence” and the Corresponding Bins Used in the Analysis of Levels of Evidence for the Different Subsets of Proteins

assigned bin	UniProt “Protein existence” value(s)	UniProt definition
protein-level evidence	experimental evidence at protein level	There is clear experimental evidence for the existence of the protein. The criteria include partial or complete Edman sequencing, clear identification by mass spectrometry, X-ray or NMR structure, good quality protein–protein interaction, or detection of the protein by antibodies.
transcript-level evidence	experimental evidence at transcript level	The existence of a protein has not been strictly proven but that expression data (such as existence of cDNA(s), RT-PCR or Northern blots) indicate the existence of a transcript.
other	protein inferred by homology	The existence of a protein is probable because clear orthologs exist in closely related species.
	protein predicted	Entries without evidence at protein, transcript, or homology levels.
	protein uncertain	The existence of the protein is unsure.