Table 1.

Statistics of unique small proteins in SmProt

Source	Start codon	Human	Mouse	Fruit fly	Rat	C. elegans	Yeast	E. coli	Zebrafish	All species examined
Ribo-seq	ATG	70,931	48,909	5269	3560	4334	4535	1881	1924	141,343
	Near-cognate codons	229,653	133,037	29,679	9910	9894	12,339	10,004	1347	435,863
Literature	ATG and near-cognate codons	38,157	8875	22,228	163	4	355	296	3612	73,690
Databases	ATG and near-cognate codons	786	797	100	271	120	336	955	64	3429
MS	ATG and near-cognate codons	768	51	66	38	0	3	0	1	927
All IDs examined	ATG and near-cognate codons	327,995	189,433	56,574	13,829	14,255	17,312	12,881	6679	638,958

Note: Small protein families from human microbiomes are not included. Near-cognate codons refer to non-ATG start codons that differ from the canonical ATG start codon by a single base but are able to initiate translation, such as TTG, GTG, CTG, AAG, AGG, ACG, ATA, ATT, and ATC. ID refers to a unique entry with identical genomic loci in one species. Ribo-seq, ribosome profiling; MS, mass spectrometry.