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Annexin V interactions with collagen
K von der Mark1, J Mollenhauer
1Institute of Experimental Medicine, Friedrich-Alexander University of Erlangen-Nürnberg, Germany. kvdmark@EXPMED.UNI-ERLANGEN.DE
Cellular and Molecular Life Sciences : CMLS
|June 1, 1997
Summary
Annexin V, a collagen-binding protein, acts as a calcium channel. Its interaction with collagen regulates calcium uptake in matrix vesicles, crucial for cartilage calcification.
Area of Science:
- Biochemistry
- Cell Biology
- Biomineralization
Background:
- Annexin V, initially identified as anchorin CII, binds to collagen.
- It is localized on the cell surface of chondrocytes, fibroblasts, and osteoblasts.
- Annexin V exhibits calcium channel activity.
Purpose of the Study:
- To investigate the role of annexin V in collagen binding and calcium transport.
- To elucidate the function of annexin V in matrix vesicle-mediated cartilage calcification.
Main Methods:
- Affinity chromatography using native type II collagen.
- Recombinant annexin V binding assays with collagen types I, II, and X.
- Studies on matrix vesicles from calcifying cartilage, including collagenase digestion and reconstitution experiments.
Main Results:
- Annexin V binds stably to native collagen type II and X, and to some extent type I.
- Calcium uptake by matrix vesicles is dependent on collagen-bound annexin V.
- Loss of collagen binding due to digestion abolished calcium influx, which was restored by adding native collagen.
Conclusions:
- Annexin V functions as a collagen-regulated calcium channel.
- It plays a significant role in matrix vesicle-initiated cartilage calcification.