Abstract
A group of proteins and polyamino acids with positively charged domains were shown to inhibit the binding of 125I-LDL to its receptor on the surface of human fibroblasts. The list of inhibitory proteins included platelet factor 4 (which has a cluster of lysine residues at its carboxyl terminus), two lysine-rich histones, poly-L-lysines of chain length greater than 4, and protamine. These proteins were effective in the concentration range of 5-50 μg/ml. Two other positively charged proteins, lysozyme and avidin, did not inhibit 125I-LDL binding. Kinetic studies suggested that protamine was not acting simply as a competitive inhibitor with regard to the LDL receptor. In light of previous data showing that polyanions such as heparin and polyphosphates also inhibit 125I-LDL binding to its cell surface receptor, the current findings suggest that charge interactions are important in this binding reaction. In a related series of studies, a number of glycoproteins and their asialo derivatives as well as a number of sugar phosphates failed to inhibit 125I-LDL binding to its receptor in fibroblasts.
Original language | English (US) |
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Title of host publication | Journal of Supramolecular and Cellular Biochemistry |
Pages | 223-234 |
Number of pages | 12 |
Volume | 8 |
Edition | 3 |
State | Published - 1978 |
ASJC Scopus subject areas
- Biochemistry