Experiment
| AccNo. |
54810 |
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| CA |
CVD |
DM |
APO |
ANG |
MI |
BD |
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| 0.78 |
0.48 |
0.21 |
0.32 |
0.30 |
0.19 |
0.39 |
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Yes |
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No |
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| Name |
PM_9371850 |
| Detection |
unspecified method, MI:0686 |
| Source |
Pubmed |
Text Id |
9371850 |
| Journal |
Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):13357-62. |
| Title |
Phytosulfokine-alpha, a sulfated pentapeptide, stimulates the proliferation of rice cells by means of specific high- and low-affinity binding sites. |
| Authors |
Matsubayashi Y, Takagi L, Sakagami Y |
| Text |
Peptide growth factors were isolated from conditioned medium derived from rice (Oryza sativa L.) suspension cultures and identified to be a sulfated pentapeptide [H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-Gln-OH] and its C-terminal-truncated tetrapeptide [H-Tyr(SO3H)-Ile-Tyr(SO3H)-Thr-OH]. These structures were identical to the phytosulfokines originally found in asparagus (Asparagus officinalis L.) mesophyll cultures. The pentapeptide [phytosulfokine-alpha (PSK-alpha)] very strongly stimulated colony formation of rice protoplasts at concentrations above 10(-8) M, indicating a similar mode of action in rice of phytosulfokines. Binding assays using 35S-labeled PSK-alpha demonstrated the existence of both high- and low-affinity specific saturable binding sites on the surface of rice cells in suspension. Analysis of [35S]PSK-alpha binding in differential centrifugation fractions suggested association of the binding with a plasma membrane-enriched fraction. The apparent Kd values for [35S]PSK-alpha binding were found to be 1 x 10(-9) M for the high-affinity type and 1 x 10(-7) M for the low-affinity type, with maximal numbers of binding sites of 1 x 10(4) sites per cell and 1 x 10(5) sites per cell, respectively. Competition studies with [35S]PSK-alpha and several synthetic PSK-alpha analogs demonstrated that only peptides that possesses mitogenic activity can effectively displace the radioligand. These results suggest that a signal transduction pathway mediated by peptide factors is involved in plant cell proliferation. |
| Mesh Terms |
Binding Sites; Cell Division/drug effects; Chromatography, High Pressure Liquid; Culture Media, Conditioned; Mass Spectrometry/methods; Oryza sativa/cytology; Plant Growth Regulators/pharmacology; Plant Proteins/pharmacology; Sulfur Radioisotopes |
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