Table 2.

Overview of the individual terms (descriptors) of the protein species nomenclature

Level	Comment	Descriptor
A: Gene	Entry name (gene name + species)	G_ACE_humana
B: Nucleotide polymorphism	SNP Accession number	SNP_rs10853044
C: Initial amino acid sequence of the protein synthesized at the ribosome	Accession number (AC) + sequence version (_1)	AC_ P12821-1_1
	Splicing variant (S) with deletion _ localisation of the deletion	SD_70-79
	Splicing variant with insertion _ localisation of the insertion	SI_43_ LLELFVMFL
	Splicing variant with an exchange of amino acids	SE_38_RQELWQG_SKEHWNQb
D: Proteolysis	Truncated amino acids: 1-17: the first 17 amino acids were removed	T_1-17
E: Posttranslational Modification (P)	Position of the modified amino acid	P_33_21c
F: Cofactor (C)	Identity of non-covalently bound cofactors	C_Zn(2x)d
G: Further descriptors	Can be added, if necessary	X, Y

^aaccording to the term in the UniProt knowledgebase [35]

^b38 indicates the number of the first exchanged amino acid of the peptide. SKEHWNQ is the peptide present in the protein species, which was substituted for RQELWQG.

^c the first number (here: 33) gives the position of the modified amino acid; the second number gives the type of the post-translational modification according to the UniMod [6] accession number (here: 21 indicating a phosphorylation)

^d here the term indicates the presence of 2 cations of Zn