Table 1.

Assignment of spectral counts to unique peptide sequences and metaclusters.

Source	Annotation	#Spectral Counts 2	# Unique Peptide Sequences 3	# Metaclusters 4
Bacterial	With useful annotation 1	32,469	10,675	1033
	Without useful annotation	8455	3541	889
Human	With useful annotation	8951	1034	212

¹ Useful annotation is based on association of a characterized gene name. ² Spectral counts are the number of spectra assigned to a peptide sequence. ³ Unique peptide sequences can be assigned to only a single protein group. ⁴ Metaclusters are created by clustering peptides sharing the same gene name and/or peptide evidence and/or the same Uniref50 identifier, independent of species assignment.