Abstract
Under physiological buffer conditions (17 mM Pi, pH 6.3), the endogenous lectin of Dictyostelium discoideum, discoidin I, binds to two types of receptors on the surface of glutaraldehyde-fixed, wild-type (NC-4) D. discoideum cells. We have designated these two types of receptors the carbohydrate or C sites and the ionic or I sites. Binding to the C sites is saturable with respect to discoidin I and is inhibited by hapten sugars (such as N-acetyl-d-galactosamine), but not by increasing buffer ionic strength with NaCl or polyelectrolytes. The number of C sites increases about 4-fold during the first 8.5 h of suspension differentiation, reaching a capacity for about 2-104 discoidin I tetramers per cell. The binding activity of the C sites is reduced about 50% by sequential NaIO4 oxidation/NaBH4 reduction of the fixed cells, but it is not reduced by CHCl3-CH3OH extraction of the fixed cells. In marked contrast, binding to the I sites appears nonsaturable with respect to discoidin I, and it is inhibited by increasing buffer ionic strength with NaCl or polyelectrolytes (such as poly-l-glutamic acid or heparin), but not by hapten sugars. The I sites are present on both vegetative and differentiated fixed cells and can bind more than 106 discoidin I tetramers per cell. The binding activity of the I sites on fixed cells is not reduced by sequential NaIO4 oxidation/NaBH4 reduction, but is reduced 70 to 90% by CHCl3-CH3OH extraction. The data suggest that the I sites represent ionic lipids that bind discoidin I electrostatically.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 121-128 |
| Number of pages | 8 |
| Journal | BBA - Biomembranes |
| Volume | 687 |
| Issue number | 2 |
| DOIs | |
| State | Published - May 7 1982 |
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Keywords
- (D. discoideum)
- Binding site
- Discoidin I-membrane interaction
- Kinetics
- Membrane receptor
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Cell Biology
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Discoidin I-membrane interactions I. Discoidin I binds to two types of receptor on fixed Dictyostelium discoideum cells. / Bartles, James R.; Frazier, William A.
In: BBA - Biomembranes, Vol. 687, No. 2, 07.05.1982, p. 121-128.Research output: Contribution to journal › Article
TY - JOUR
T1 - Discoidin I-membrane interactions I. Discoidin I binds to two types of receptor on fixed Dictyostelium discoideum cells
AU - Bartles, James R.
AU - Frazier, William A.
PY - 1982/5/7
Y1 - 1982/5/7
N2 - Under physiological buffer conditions (17 mM Pi, pH 6.3), the endogenous lectin of Dictyostelium discoideum, discoidin I, binds to two types of receptors on the surface of glutaraldehyde-fixed, wild-type (NC-4) D. discoideum cells. We have designated these two types of receptors the carbohydrate or C sites and the ionic or I sites. Binding to the C sites is saturable with respect to discoidin I and is inhibited by hapten sugars (such as N-acetyl-d-galactosamine), but not by increasing buffer ionic strength with NaCl or polyelectrolytes. The number of C sites increases about 4-fold during the first 8.5 h of suspension differentiation, reaching a capacity for about 2-104 discoidin I tetramers per cell. The binding activity of the C sites is reduced about 50% by sequential NaIO4 oxidation/NaBH4 reduction of the fixed cells, but it is not reduced by CHCl3-CH3OH extraction of the fixed cells. In marked contrast, binding to the I sites appears nonsaturable with respect to discoidin I, and it is inhibited by increasing buffer ionic strength with NaCl or polyelectrolytes (such as poly-l-glutamic acid or heparin), but not by hapten sugars. The I sites are present on both vegetative and differentiated fixed cells and can bind more than 106 discoidin I tetramers per cell. The binding activity of the I sites on fixed cells is not reduced by sequential NaIO4 oxidation/NaBH4 reduction, but is reduced 70 to 90% by CHCl3-CH3OH extraction. The data suggest that the I sites represent ionic lipids that bind discoidin I electrostatically.
AB - Under physiological buffer conditions (17 mM Pi, pH 6.3), the endogenous lectin of Dictyostelium discoideum, discoidin I, binds to two types of receptors on the surface of glutaraldehyde-fixed, wild-type (NC-4) D. discoideum cells. We have designated these two types of receptors the carbohydrate or C sites and the ionic or I sites. Binding to the C sites is saturable with respect to discoidin I and is inhibited by hapten sugars (such as N-acetyl-d-galactosamine), but not by increasing buffer ionic strength with NaCl or polyelectrolytes. The number of C sites increases about 4-fold during the first 8.5 h of suspension differentiation, reaching a capacity for about 2-104 discoidin I tetramers per cell. The binding activity of the C sites is reduced about 50% by sequential NaIO4 oxidation/NaBH4 reduction of the fixed cells, but it is not reduced by CHCl3-CH3OH extraction of the fixed cells. In marked contrast, binding to the I sites appears nonsaturable with respect to discoidin I, and it is inhibited by increasing buffer ionic strength with NaCl or polyelectrolytes (such as poly-l-glutamic acid or heparin), but not by hapten sugars. The I sites are present on both vegetative and differentiated fixed cells and can bind more than 106 discoidin I tetramers per cell. The binding activity of the I sites on fixed cells is not reduced by sequential NaIO4 oxidation/NaBH4 reduction, but is reduced 70 to 90% by CHCl3-CH3OH extraction. The data suggest that the I sites represent ionic lipids that bind discoidin I electrostatically.
KW - (D. discoideum)
KW - Binding site
KW - Discoidin I-membrane interaction
KW - Kinetics
KW - Membrane receptor
UR - http://www.scopus.com/inward/record.url?scp=49049134783&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=49049134783&partnerID=8YFLogxK
U2 - 10.1016/0005-2736(82)90537-5
DO - 10.1016/0005-2736(82)90537-5
M3 - Article
AN - SCOPUS:49049134783
VL - 687
SP - 121
EP - 128
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
SN - 0005-2736
IS - 2
ER -