Table 2.
Identification of nucleolin associated proteins in the 500-kDa complex.
| Protein Band (MW) | Obtained Sequence1/Medline Sequence2 |
|---|---|
| Band 5 (90-kDa) | MHRPFXX1 |
| 1-MHRNFRK2 = Wnt related protein A3 | |
| Band 6 (85-kDa) | MRPMTQIIVQD1 |
| 1-MRPMTFIVGLK2 = Wnt related protein B4 | |
| Band 7 (80-kDa) | VRSGNKAAVVLXMDVXFTMS1 |
| 1-MVRSGNKAAVVLCMDVGFTMS = Ku805 | |
| Band 8 (72-kDa) | ASGGSGGVXVPA1 |
| 1-MASGGSGGVSVPA2 = SRP726 | |
| Band 9 (68-kDa) | AAEKQVPGGXXGGGS1 |
| 1-MAAEKQVPGGGGGGGS2 = SRP686 | |
| Band 11 (32-kDa) | LHTDGDKAFVDFLSD1 |
| 74-LHTDGDKAFVDFLSD2 = p32/p33/HABP1/gC1q-R7 | |
| Bands 12 (25-kDa): | ARGPKKHLK1 |
| 1-MARGPKKHLK2 = S48 | |
| KLNISFPAL1 | |
| 1-MKLNISFPAL2 = S68 |
By the capacity of the HB-19/Btn to bind surface nucleolin, the 500-kDa complex was recovered from the cell surface and purified using avidin-agarose. After analysis by SDS-PAGE, several protein bands of 90-, 85-, 80-, 72-, 68-, 32, and 25-kDa were processed for NH2-terminal microsequencing (Methods; Additioal file 2, Figure 2S). These protein bands were identified as Wnt related proteins, Ku80, SRP68, SRP72, p32/p33/HABP1/gC1q-R, and ribosomal proteins S4 and S6.
1 The obtained NH2-terminal sequence.
2 The NH2-terminal sequence in the Medline.
3 The obtained MHRPFXX sequence shares homology to the N-terminal sequence of human Wnt-7b (MHRNFR) [87].
4 The obtained MRPMTQIIVQD sequence is homologous in its first 5 amino acid residues with the N-terminal sequence (MRPMTFIVGLK) of Wnt-1 of the Mexican axolotls Ambystoma mexicanum [88]. Consequently, the isolated protein appears to correspond to a human Wnt-related protein that remains to be described.
5 The 80-kDa subunit of the Ku autoantigen [89]
6 The 68- and 72-kDa subunit of the signal recognition particle [60].
7 Referred in the literature as the protein p32 associated with the splicing factor SF2, the hyaluronan binding protein 1 (HABP1) and the receptor for complement component C1q (gC1q-R)[90].
8 Ribosomal proteins S4 and S6 [91].