Table 1.

Summary of myofilament protein proteoforms assigned based on either their accurate mass measurements or MS/MS analysis results (annotated with asterisk).

Protein #	Protein ID	Accession Number	Modifications	Expt’l Mr (Da)	Calc’d Mr (Da)	Error (ppm)
1	fsTnT1	A0A2K5WPG3	+Ac1-Met2 −98 Da from pfsTnT1	29014.07	29014.22	5.2
			+Ac-Met	29032.11	29032.23	4.1
			+P3+Ac-Met	29112.05	29112.08	1.0
2	fsTnT2	A0A2K5WPF7	+Ac-Met-98 Da from pfsTnT2	29628.41	29628.48	2.4
			+Ac-Met	29646.40	29646.49	3.0
			+P+Ac-Met	29726.35	29726.45	3.4
3	fsTnT3	XM_015113340#	+Ac-Met-98 Da from pfsTnT3	29771.51	29771.62	3.7
			+Ac-Met	29789.50	29789.63	4.4
			+P+Ac-Met	29869.51	29869.59	2.7
4	fsTnT4	NA§	−98 Da from pfsTnT4	29894.38	NA	NA
				29912.39	NA	NA
			+P	29992.38	NA	NA
5	fsTnT5	A0A2K5WPH1	+Ac-Met-98 Da from pfsTnT5	30578.80	30578.91	3.6
			+Ac-Met	30596.80	30596.92	3.9
			+P+Ac-Met*	30676.75	30676.89	4.6
6	fsTnT6	F6U551	+Ac-Met-98 Da from pfsTnT6	31193.01	31193.17	5.1
			+Ac-Met	31211.12	31211.18	1.9
			+P+Ac-Met	31291.00	31291.14	4.5
7	ssTnT	F7HR10	+Ac-Met-98 Da from pssTnT	31013.92	31014.02	3.2
			+Ac-Met	31031.91	31032.03	3.9
			+P+Ac-Met*	31111.87	31111.99	3.9
8	ssTnI	I2CW22	−Met*	21547.44	21547.52	3.7
9	fsTnI	A0A1D5QTK6	+Ac-Met*	21209.77	21209.84	3.3
			+SSG4+Ac-Met	21514.83	21514.91	3.7
10	PDLIM5	F6Z147	+Ac-Met*	23703.41	23703.44	1.3
			+Me5+Ac-Met	23717.42	23717.45	1.3
11	PDLIM7	NA	+Ac*	21106.86	21106.93	3.3
			+P+Ac	21186.82	21186.90	3.8
12	LDB3	075112-6	+Ac-Met*	30890.74	30890.78	1.3
			+P+Ac-Met	30970.69	30970.75	1.9
13	αTpm	P04692	+Ac*	32702.63	32702.69	1.8
			+P+Ac	32782.58	32782.65	2.1
14	γTpm	P06753	+Ac-Met*	32840.68	32840.75	2.1
15	βTpm	P07951	+Ac*	32872.52	32872.58	1.8
16	MLC-1S	A0A1D5RAU6	+(Me)36-Met*	21855.91	21855.97	2.7
17	MLC-1F	G7N8T7	+(Me)3-Met*	20858.58	20858.64	2.9
18	MLC-2F	F7EI96	+(Me)3-Met*	18838.36	18838.38	1.1
			+P+(Me)3-Met*	18918.33	18918.35	1.1
			+2P+(Me)3-Met*	18998.29	18998.31	1.1
19	MLC-2S	A0A1D5RDY5	+Dea8+(Me)3-Met*	18759.38	18759.38	0.0
			+P+Dea+(Me)3-Met*	18839.35	18839.34	0.5
			+2P+Dea+(Me)3-Met	18919.32	18919.31	0.5
20	MLC-3F	F7B2B7	+Ac-Met*	16570.11	16570.17	3.6
21	αactin	F7HM15	+Ac+Me-Met-Cys*7	41845.56	41845.83	6.5
22	fsTnC	F7HGA7	+Ac-Met*	18021.21	18021.32	6.1
23	ssTnC	G7MV95	+Ac*	18450.41	18450.51	5.4

^#Accession number of transcript variant X4 from NCBI nucleotide database. Protein accession number was not found.

^§Protein sequence was not found based on monoisotopic mass of the intact protein.

^*Proteoforms identified by MS/MS analysis.

¹Acetylation

²Methionine

³Phosphorylation

⁴Gluthathionylation

⁵Methylation

⁶Tri-methylation

⁷Cysteine

⁸Deamidation