Title | Imaging and mapping heparin-binding sites on single fibronectin molecules with atomic force microscopy |
Publication Type | Journal Article |
Year of Publication | 2000 |
Authors | Lin H, Lal R, Clegg DO |
Journal | Biochemistry |
Volume | 39 |
Issue | 12 |
Pagination | 3192-6 |
Date Published | 2000 Mar 28 |
ISSN | 0006-2960 |
Keywords | Animals, Binding Sites, Cattle, Dimerization, Disulfides, Fibronectins, Gold Colloid, Heparin, Image Enhancement, Microscopy, Atomic Force, Peptide Fragments, Peptide Mapping, Random Allocation, Serum Albumin |
Abstract | Fibronectin is composed of multiple homologous repeats and contains many functional domains. Two major heparin-binding domains have previously been identified: the Hep I site near the amino terminus and the Hep II site near the carboxyl terminus. The Hep II site has been considered the high-affinity heparin-binding site based on studies of fibronectin fragments. However, few studies have been carried out on heparin binding by intact fibronectin. We imaged single fibronectin molecules as well as heparin-coated gold particles bound to whole dimeric plasma fibronectin molecules with tapping mode atomic force microscopy. We observed heparin-gold particles preferentially bound at two locations that correspond to the Hep I and Hep II sites. Quantitative analysis of images of individual fibronectin-heparin-gold complexes showed that almost twice as many heparin-gold particles bound to the N-terminal Hep I site compared to the Hep II site. In contrast to previous findings with fibronectin fragments, these results suggest that the Hep I site has a binding affinity higher than or comparable to the Hep II site in the intact fibronectin molecule. |
Alternate Journal | Biochemistry |
PubMed ID | 10727210 |
Grant List | EY066570 / EY / NEI NIH HHS / United States EY09736 / EY / NEI NIH HHS / United States GM056290 / GM / NIGMS NIH HHS / United States |