TABLE 3.
Relative protein levels in mouse (C57Bl6/J) pancreas
Insulin and glucagon were among the most abundant proteins in mouse islets as expected considering that the main function of the islets is to secrete these hormones. Proteins involved in exocytosis (e.g. RAB27A) and in the filling of granules with zinc (the vesicular zinc transporter ZnT8) were also found at high levels in islets in agreement with the high number of secretory granules. Note that ASCT2 (Slc1a5) was detected in both islets and whole pancreas and that ASCT1 (Slc1a4) was detected in whole pancreas, whereas the other members of the same protein family (EAAT1–5) were not. Also note that the VGLUT1–3 and GABA (VGAT) transporters were below the detection limit. In contrast, both glutamine transporters (Slc38a2 and -3), mitochondrial glutamate carriers (AGC1, aralar1; AGC2, citrin; and GC1), and enzymes involved in glutamate metabolism (Glud1, Glul, and Gs2) were detected. Peptide numbers in the last columns indicate the maximum number of different peptides identified in one sample and indicate another rough estimate of relative protein quantities (this number does not preclude the presence of multiple peptide forms like charge states, modifications, etc.). The complete proteome list is available in supplemental Table S1. ND, not detected; iso, isoform.
| Protein name | Islets |
Whole pancreas |
Ratio islet/pancreas | No. of peptides |
|||
|---|---|---|---|---|---|---|---|
| Rank | Intensity | Rank | Intensity | Islet | Pancreas | ||
| Insulin1 | 3 | 1.22E + 08 | 459 | 1.89E + 06 | 64a | 5 | 2 |
| Glucagon | 5 | 1.06E + 08 | 537 | 1.49E + 06 | 71a | 18 | 6 |
| Insulin2 | 6 | 8.02E + 07 | 613 | 1.26E + 06 | 64a | 7 | 4 |
| RAB27A | 150 | 1.13E + 07 | 918 | 6.28E + 05 | 18a | 30 | 16 |
| Got2 | 226 | 7.65E + 06 | 371 | 2.55E + 06 | 3.0 | 25 | 18 |
| AGC1 (Slc25a12) | 256 | 6.86E + 06 | 888 | 6.56E + 05 | 10.5a | 35 | 18 |
| Glud1 | 308 | 5.28E + 06 | 271 | 4.01E + 06 | 1.3 | 27 | 26 |
| Got1 | 473 | 3.10E + 06 | 394 | 2.31E + 06 | 1.3 | 22 | 19 |
| Pycr2 | 570 | 2.45E + 06 | 570 | 1.39E + 06 | 1.8 | 14 | 13 |
| Glul | 760 | 1.62E + 06 | 3288 | 2.34E + 04 | 69a | 15 | 3 |
| ZnT8 (Slc30a8) | 768 | 1.59E + 06 | 4975 | 1.91E + 03 | >100a | 8 | 1 |
| GC1 (Slc25a22) | 1217 | 6.51E + 05 | 2476 | 5.92E + 04 | 11.0 | 12 | 4 |
| GLUT2 (Slc2a2) | 1352 | 5.19E + 05 | ND | ND | 8 | ||
| AGC2 (Slc25a13) | 1366 | 5.03E + 05 | 1575 | 2.00E + 05 | 2.5 ns | 18 | 13 |
| ZnT7 (Slc30a7) | 1377 | 4.98E + 05 | 4034 | 1.02E + 04 | 48.8 | 8 | 3 |
| Slc7a14 | 1444 | 4.58E + 05 | ND | ND | |||
| MCT10 (Slc16a10) | 1721 | 3.00E + 05 | 5354 | 1.64E + 02 | >100a | 6 | 2 |
| Aldh4a1 | 1770 | 2.85E + 05 | 1396 | 2.68E + 05 | 1.1 | 2 | 2 |
| Slc38a10 | 1938 | 2.30E + 05 | 3774 | 1.35E + 04 | 17.1 | 18 | 3 |
| SNAP25 | 2420 | 1.29E + 05 | ND | ND | 3 | ||
| ZnT6 (Slc30a6) | 2685 | 9.79E + 04 | 2879 | 3.70E + 04 | 2.64 | 3 | 2 |
| PAT1 (Slc36a1) | 2690 | 9.71E + 04 | ND | ND | 2 | ||
| SNAT2 (Slc38a2) | 3054 | 6.79E + 04 | 1904 | 1.23E + 05 | 0.55 | 2 | 3 |
| SNAT3 (Slc38a3) | 3124 | 6.35E + 04 | 1333 | 2.93E + 05 | 0.22a | 3 | 3 |
| SNAT5 (Slc38a5) iso1 | 3840 | 3.34E + 04 | 1106 | 4.25E + 05 | 0.08a | 4 | 7 |
| ASCT2 (Slc1a5) | 3956 | 2.90E + 04 | 2193 | 8.35E + 04 | 0.35 | 3 | 4 |
| SNAT4 (Slc38a4) | 4120 | 2.47E + 04 | ND | ND | 4 | ||
| NTT4 (Slc6a17) | 4250 | 2.22E + 04 | ND | ND | |||
| TAUT (Slc6a6) | 4991 | 1.01E + 04 | ND | ND | 2 | ||
| GLYT1 (Slc6a9) | 5179 | 8.78E + 03 | 2395 | 6.43E + 04 | 0.14a | 3 | 3 |
| Gls2 | 5335 | 7.35E + 03 | 2601 | 4.96E + 04 | 0.15a | 5 | 13 |
| MCT1 (Slc16a1) | 5732 | 4.40E + 03 | 4502 | 5.31E + 03 | 0.83 | 3 | 2 |
| ASCT1 (Slc1a4) | ND | ND | 3746 | 1.39E + 04 | 2 | ||
| SNAT5 (Slc38a5) iso2 | ND | ND | 4622 | 4.40E + 03 | 1 | ||
| Gls1 | ND | ND | ND | ND | |||
| VGLUT1 (Slc17a7) | ND | ND | ND | ND | |||
| VGLUT2 (Slc17a6) | ND | ND | ND | ND | |||
| VGLUT3 (Slc17a8) | ND | ND | ND | ND | |||
| EAAT1 (Slc1a3) | ND | ND | ND | ND | |||
| EAAT2 (Slc1a2) | ND | ND | ND | ND | |||
| EAAT3 (Slc1a1) | ND | ND | ND | ND | |||
| EAAT4 (Slc1a6) | ND | ND | ND | ND | |||
| EAAT5 (Slc1a7) | ND | ND | ND | ND | |||
| GAT3 (Slc6a11) | ND | ND | ND | ND | |||
| GLYT2 (Slc6a5) | ND | ND | ND | ND | |||
| VGAT (Slc32a1) | ND | ND | ND | ND | |||
| xCT (Slc7a11) | ND | ND | ND | ND | |||
a Indicates significant expression differences when comparing exclusively shared peptides.