Table 4. Proteins identified by LC-MS/MS in the apoplast of Arabidopsis thaliana leaves.
| Spot No | Similarity to | Locus | Proteinscore | expectedMw (Da) | Signal peptide |
| 1 | Thioglucosidase | At5g26000 | 123 | 61664 | S (RC 1) |
| 2 | Subtilase | At5g67360 | 301 | 80050 | S (RC 1) |
| 3 | Subtilase | At5g67360 | 241 | 80050 | S (RC 1) |
| 4 | β-1,4-xylosidase | At3g19620 | 243 | 97359 | S (RC 1) |
| 5 | Aspartyl protease | At5g10760 | 102 | 50411 | S (RC 2) |
| 6 | Peptidyl-prolyl cis-trans isomerase | At3g01480 | 62 | 48180 | C (RC 1) |
| 7 | Pepsin A | At3g18490 | 62 | 53942 | C (RC 5) |
| 8 | Pepsin A | At3g18500 | 63 | 53942 | M (RC 4) |
| 9 | Sedoheptulose-bisphosphatase precursor | At3g55800 | 168 | 42787 | C (RC 1) |
| 10 | Curculin-like | At1g78830 | 169 | 51007 | S (RC 1) |
| 11 | Curculin-like | At1g78830 | 203 | 51007 | S (RC 1) |
| 12 | Carboxylic ester hydrolase | At1g29660 | 270 | 40630 | S (RC 2) |
| 13 | β-1,3-glucanase 2 (PR2) | At3g57260 | 389 | 37373 | S (RC 1) |
| 14 | Oxygen-evolving enhancer protein (OEE33) | At5g66570 | 66 | 35285 | C (RC 2) |
| 15 | PR5, thaumatin-like | At1g75040 | 576 | 26148 | S (RC 1) |
| 16 | Chaperonin 10 | At1g14980 | 101 | 26913 | M (RC 3) |
| 17 | Oxygen-evolving enhancer protein 2 (PSBP) | At1g06680 | 136 | 28249 | C (RC 2) |
| 18 | Rubisco (large subunit) | AtCg00490 | 113 | 53424 | _ (RC2)* |
| 19 | Serine hydroxyl-methyltransferase (SHM 1) | At4g37930 | 44 | 57535 | M (RC 4) |
| 21 | Pepsin A, aspartyl protease | At1g09750 | 39 | 48429 | S (RC 1) |
| 22 | Pepsin A, aspartyl protease | At1g09751 | 104 | 48429 | S (RC 1) |
| 23 | Carboxylic ester hydrolase | At2g46930 | 78 | 46827 | S (RC 1) |
| 24 | Unknown protein | At3g08030 | 83 | 39326 | S (RC 2) |
| 25 | Protein binding | At3g20820 | 54 | 40464 | S (RC 2) |
| 26 | Pepsin A, aspartyl protease | At1g09750 | 70 | 48429 | S (RC 1) |
| 28 | β-1,3-glucanase 3 | At3g57260 | 359 | 37722 | S (RC 1) |
| 29 | Carboxylic ester hydrolase | At1g29670 | 539 | 40417 | S (RC 1) |
| 30 | Lectin like protein | At3g15356 | 238 | 29650 | S (RC 1) |
| 31 | Lectin like protein | At3g15356 | 252 | 29650 | S (RC 1) |
| 32 | Carbohydrate binding | At5g03350 | 91 | 30200 | S (RC 2) |
| 33 | MERI5b; hydrolase | At4g30270 | 177 | 30850 | S (RC 1) |
| 34 | Chitinase | At2g43590 | 61 | 29304 | S (RC 1) |
| 35 | Peptidylprolyl isomerase (ROC4) | At3g62030 | 44 | 28532 | C (RC 1) |
| 36 | Endopeptidase inhibitor | At1g17860 | 119 | 22410 | S (RC 2) |
| 37 | Hypothetical protein | At1g33640 | 53 | 56113 | S (RC 2) |
| 38 | β-1,3-glucanase 2 (PR2) | At3g57260 | 140 | 37373 | S (RC 1) |
| 39 | Peroxidase, putative, PA2 | At5g06720 | 69 | 32504 | S (RC 2) |
*encoded in the chloroplast genome.
Apoplastic washing fluids from mock-infected plants were separated by 2-D-gel electrophoresis, picked, trypsinated and used for determination fragment composition by LC-MS/MS. Identification was achieved by data bank queries as outlined under materials and methods. Spot numbers refer to those shown in Fig. 1. S, C, and M indicate predicted signal peptides for the secretory pathway, chloroplasts or mitochondria, respectively. RC indicates reliability classes for the prediction of localization (1 = high, 5 = low). Peptides are shown in Table S1.