On the binding of dolichol by human serum.

The presence of a dolichol binding system is demonstrated in human serum. The dolichol binding exhibits normal saturation kinetics with an apparent affinity constant Kd of 6.9 X 10(-6) M. Optimal binding is obtained at pH 7.4 and 5 degrees C. After binding the [3H]dolichol cannot be chased by unlabelled dolichol. The selectivity is examined by competition studies showing that only dolichyl derivatives equally compete for binding sites. From buoyant density centrifugation and gel filtration it is deduced that the dolichol binding is due to a serum protein fraction, displaying the characteristics of VLDL.