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.
N1 - Funding Information:
We thank Barbara Santoro and Anita Turner for excellentte chnicaal ssistanceW, alterNulty for performingth es edimentatioenq uilibriuma nalyses, Dr. Steve Rosen for providing the D. discoideum spore stocks, Mike Kastan and Dr. Michael Lieberman for providing the E. coli strain B/r, and Drs. Mathews and Cifonelli for providingt he references tandardg rade dermatans ulfate.This work was supportedb y Grant/',IS 13269 from the National Instituteso f Health and Grant PCM78-04303 from the National Science Foundation to W.A.F.W.A.F. is an EstablishedIn vestigatoor f the AmericanH eartAssociation.
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
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U2 - 10.1016/0005-2736(82)90537-5
DO - 10.1016/0005-2736(82)90537-5
M3 - Article
AN - SCOPUS:49049134783
SN - 0005-2736
VL - 687
SP - 121
EP - 128
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 2
ER -