Table 1. Characterization of the 36 skeletal organic matrix proteins (SOMPs).
| UniprotKB accession | Name (Abbrev.) | Number of residues | Mw* (KDa) | pI* | Major* | Putative PTM | Other sequence properties |
| number | (status) | aa (%) | |||||
| B3EWY6 | Skeletal acidic Asp-rich Protein 1 (SAARP 1) | 386 | 40.1 | 3.92 | Asp (20.4) | Glycosaminoglycan site (2), N-glycosylation (3), Phosphorylation: Ser (22), Thr (5), Tyr (3) | SP [1]–[24], GPI anchor (S, 359), Asp-rich [60–108, 260–288], ND repeat [67–103] |
| B3EWY7 | Acidic skeletal organic matrix protein (Acidic SOMP) | 359 | 36.1 | 4.13 | Asp (9.9) | Glycosaminoglycan site (6), N-glycosylation (5), O-Fucosylation (1), Phosphorylation: Ser (18), Thr (5), Tyr (2) | SP [1]–[26], GPI anchor (N, 333), Asp-rich [61–86, 246–262, 341–355] |
| B3EWY8 | Skeletal acidic Asp-rich Protein 2 (SAARP2) | 390 (Fragment) | 42.4 | 4.24 | Asp (21.1) | Glycosaminoglycan site (2), N-glycosylation (3), Phosphorylation: Ser (15), Thr (6), Tyr (1) | SP [1]–[16], TM [367–389], Asp-rich [48–83, 91–124, 271–292], DDK repeat [97–107] |
| B3EWY9 | Mucin-like | 1594 (Fragment) | - | - | - | ASX hydroxylation (3), Glycosaminoglycan site (7), N-glycosylation (12), O-Fucosylation (1), Phosphorylation: Ser (47), Thr (25), Tyr (9) | TM [1531–1553] |
| B3EWZ0 | Secreted acidic protein 1 (Amil-SAP1) | 168 (Fragment NT) | - | - | - | Glycosaminoglycan site (4) N-glycosylation (1) Phosphorylation: Ser (7), Thr (4), Tyr (0) | SP [1]–[20], GPI anchor (G, 119), RGD motif [119–121] |
| B3EWZ1 | 142 (Fragment CT) | - | - | - | Glycosaminoglycan site (2) N-glycosylation (1) Phosphorylation: Ser (4), Thr (0), Tyr (2) | TM [124–141], G[D,7]S repeat [139–168] | |
| B3EWZ2 | Uncharacterized skeletal organic matrix protein-8 (USOMP-8) | 214 | 20.9 | 5.26 | Ser (8.9) | Glycosaminoglycan site (2) N-glycosylation (3) | SP [1]–[24], LCR [119–133] |
| B3EWZ3 | Coadhesin | 1675 (Fragment) | - | - | - | Peptide C-terminal amidation (1) Glycosaminoglycan site (5) Phosphorylation: Ser (60), Thr (30), Tyr (13) | TM [1361–1383] |
| B3EWZ4 | Secreted acidic protein 2 (Amil-SAP2) | 168 (Fragment) | - | - | - | Glycosaminoglycan site (6), Phosphorylation: Ser (11), Thr (2), Tyr (3) | SG[D,6]GD repeat [4]–[33] |
| B3EWZ5 | MAM and LDL-receptor domain- containing protein 1 | 5145 (Fragment) | - | - | - | Glycosaminoglycan site (3), N-glycosylation (1), Phosphorylation:? | RGD motif [47]–[49], P[T,2] repeat [1099–1110], [P,2][T,2] repeat [2512–2522] |
| B3EWZ6 | MAM and LDL-receptor domain- containing protein 2 | 7311 (Fragment) | - | - | - | Glycosaminoglycan site (6), N-glycosylation (2), O-Fucosylation site (1), Phosphorylation:? | P[T,2] repeat [178–189], [P,2][T,2] repeat [2261–2271] |
| B3EWZ7 | Threonine-rich protein | 288 (Fragment) | - | - | - | Glycosaminoglycan site (2), N-glycosylation (10), Phosphorylation: Ser (9), Thr (30), Tyr (0) | SP [1]–[21], Thr-rich [151–262], TEAP[T,2] repeat [168–261] |
| B3EWZ8 | Ectin | 400 (Fragment) | - | - | - | Glycosaminoglycan site (4), N-glycosylation (1), Phosphorylation: Ser (17), Thr (7), Tyr (5) | SP [1]–[21] |
| B3EWZ9 | Hephaestin-like | 1114 | 122.0 | 5.83 | Gly (8.5) | Peptide C-terminal amidation (3), Glycosaminoglycan site (5), N-glycosylation (2), Phosphorylation: Ser (28), Thr (17), Tyr (14) | SP [1]–[26], TM [1090–1112], GPI anchor (A, 1090) |
| B3EX00 | Uncharacterized skeletal organic matrix protein-1 (USOMP-1) | 448 (Fragment) | - | - | - | Glycosaminoglycan site (5), N-glycosylation (8), Phosphorylation: Ser (19), Thr (6), Tyr (0) | LCR [101–120, 318–344, 428–448] |
| B3EX01 | CUB domain-containing protein | 409 | 42.8 | 5.05 | Thr (13.6) | Glycosaminoglycan site (3), N-glycosylation (6), Phosphorylation: Ser (17), Thr (17), Tyr (5) | SP [1]–[18], LCR [91–104, 150–229, 349–359, 392–409] |
| B3EX02 | MAM and fibronectin- containing protein | 422 (Fragment) | - | - | - | Peptide C-terminal amidation (1), Glycosaminoglycan site (3), N-glycosylation (6), Phosphorylation: Ser (18), Thr (4), Tyr (5) | |
| B7W112 | Glu-rich protein | 522 | 58.3 | 3.96 | Glu (22.3) | Glycosaminoglycan site (1), Phosphorylation: Ser (35), Thr (5), Tyr (10) | SP [1]–[16], Glu-rich [107–134, 152–201, 227–262], DEAE repeat [358–425] |
| B7W114 | Cephalotoxin-like protein | 473 (Fragment) | - | - | - | Glycosaminoglycan site (5), N-glycosylation (1), Phosphorylation: Ser (16), Thr (3), Tyr (8) | SP [1]–[21] |
| B7WFQ1 | Uncharacterized skeletal organic matrix protein-2 (USOMP-2) | 505 | 52.9 | 5.90 | Cys (10.5) | Peptide C-terminal amidation (1), Glycosaminoglycan site (7), N-glycosylation (7), Phosphorylation: Ser (12), Thr (6), Tyr (3) | SP [1]–[19] |
| B8RJM0 | Uncharacterized skeletal organic matrix protein-3 (USOMP-3) | 433 (Fragment) | - | - | - | Glycosaminoglycan site (6), N-glycosylation (2), Phosphorylation: Ser (22), Thr (8), Tyr (5) | SP [1]–[28], TM [275–297] |
| B8UU51 | Galaxin 2 | 275 | 26.8 | 8.18 | Cys (11.8) | Glycosaminoglycan site (2), N-glycosylation (2), Phosphorylation: Ser (4), Thr (2), Tyr (3) | SP [1]–[20], 5 di-Cys repeats |
| B8UU59 | polycystic kidney disease 1-related skeletal organic matrix protein (PKD1-related protein) | 3029 (Fragment) | - | - | - | Peptide C-terminal amidation (2), Glycosaminoglycan site (45), N-glycosylation (46), O-Fucosylation site (2), Phosphorylation: Ser (130), Thr (37), Tyr (31) | SP [1]–[21], TM [1684–1706, 1896–1913, 1933–1955, 2103–2125, 2140–2162, 2250–2272, 2457–2479, 2491–2513, 2545–2564, 2585–2607, 2651–2673], RGD motif [2852–2854] |
| G8HTB6 | Zona pellucida domain-containing protein | 414 | 43.8 | 4.92 | Ser (10.3) | Glycosaminoglycan site (3), Phosphorylation: Ser (18), Thr (7), Tyr (7) | SP [1]–[17], TM [366–388], LCR [39]–[64] |
| B8UU74 | Uncharacterized skeletal organic matrix protein-4 (USOMP-4) | 204 (Fragment) | - | - | - | Phosphorylation: Ser (3), Thr (3), Tyr (1) | LCR [17]–[34] |
| D9IQ16 | Galaxin | 338 | 32.7 | 5.15 | Cys (12.7) | Glycosaminoglycan site (1), N-glycosylation (1), Phosphorylation: Ser (7), Thr (1), Tyr (3) | SP [1]–[23], 9 di-Cys repeats |
| B8UU78 | EGF and laminin G domain-containing protein | 1124 | 123.8 | 6.38 | Gly (8.5) Ser (8.5) | ASX hydroxylation (1), Glycosaminoglycan site (16), N-glycosylation (3), Phosphorylation: Ser (42), Thr (14), Tyr (17) | TM [1056–1078], LCR [423–434, 1110–1121] |
| B8V7P3 | Putative carbonic anhydrase | 148 (Fragment) | - | - | - | Glycosaminoglycan site (1), Phosphorylation: Ser (2), Thr (2), Tyr (0) | |
| B8V7Q1 | Protocadherin-like | 4467 | 486.1 | 4.98 | Val (9.7) | Peptide C-terminal amidation (1), Glycosaminoglycan site (27), Phosphorylation? | SP [1]–[22], TM [4257–4279], NGR motif [1515–1517, 3798–3800] [S,2][G,2]SVGV[S[G,2],2]ASV[G,2]SI[G,2], ASG repeat [4092–4136], ILV[I,2]GA repeat [4263–4276] |
| B8V7R6 | Collagen alpha-1 chain | 888 (Fragment) | - | - | - | Peptide C-terminal amidation (3), Glycosaminoglycan sites (17), N-glycosylation (3), Phosphorylation: Ser (36), Thr (9), Tyr (7) | LCR [98–114, 225–279, 302–331, 422–441, 459–489], G[P,2] repeat [609–621], NGR motif [413–415, 452–454], RGD [221–223] |
| B8V7S0 | CUB and peptidase domain-containing protein 1 | 435 (Fragment) | - | - | - | N-glycosylation (2), Phosphorylation: Ser (11), Thr (11), Tyr (6) | LCR [384–405] |
| B7T7N1 | MAM and fibronectin containing protein 2 | 112 (Fragment) | - | - | - | Glycosaminoglycan site (4), N-glycosylations (3), Phosphorylation: Ser (3), Thr (1), Tyr (1) | |
| B8VIV4 | CUB and peptidase domain-containing protein 2 | 389 (Fragment) | - | - | - | Phosphorylation: Ser (4), Thr (3), Tyr (5) | |
| B8VIU6 | Uncharacterized skeletal organic matrix protein-5 (USOMP-5) | 256 | 25.2 | 8.92 | Ser (11.9) | Glycosaminoglycan site (3), N-glycosylations (6), Phosphorylation: Ser (10), Thr (6), Tyr (1) | SP [1]–[21] |
| B8VIW9 | Neuroglian-like | 1280 | 140.4 | 5.65 | Ser (8.0) | Peptide C-terminal amidation (2), Glycosaminoglycan site (2), Phosphorylation: Ser (58), Thr (29), Tyr (17) | SP [1]–[19], TM [4257–4279], NGR motif [1196–1198] |
| B8VIX3 | Uncharacterized skeletal organic matrix protein-6 (USOMP6) | 436 | 48.1 | 9.04 | Glu (14.4) | Peptide C-terminal amidation (1), N-glycosylations (4), Phosphorylation: Ser (19), Thr (9), Tyr (1) | SP [1]–[20], LCR [316–326, 414–427] |
| B8WI85 | Uncharacterized skeletal organic matrix protein-7 (USOMP7) | 422 | 44.3 | 9.26 | Val (9.0) | Glycosaminoglycan site (7), N-glycosylation (1), Phosphorylation: Ser (11), Thr (1), Tyr (10) | SP [1]–[23] |
Computed parameters: molecular weight (Mw), isoelectric point (pI), most abundant amino acid (Major aa%), post-translational modifications (PTM) and other sequence features: signal peptide (SP), transmembrane domain (TM), glycosylphosphatidylinositol (GPI anchor), complexity regions (LCR), regions of biased composition, motifs and repeats.
*Properties calculated based on the primary sequence of the mature protein, i.e. without peptide signal.