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The binding of the amyloid protein precursor (APP) to heparan sulfate proteoglycans has been shown to stimulate the neurite-promoting activity of APP. In this study, proteoglycans that bind with high affinity to APP were characterized. Conditioned medium from cultures of postnatal day 3 mouse brain cells was applied to an affinity column containing a peptide homologous to a heparin-binding domain of APP. A fraction 17-fold enriched in proteoglycans was recovered by elution with a salt gradient. APP bound saturably and with high affinity to the affinity-purified proteoglycan fraction. Scatchard analysis of the binding showed that APP bound to high- and low-affinity sites with equilibrium dissociation constants of 1.4 × 10−11 and 6.5 × 10−10M, respectively. APP, in conjunction with the affinity-purified proteoglycan fraction, promoted neurite outgrowth. The affinity-purified proteoglycan fraction contained a heparan sulfate proteoglycan and a chondroitin sulfate proteoglycan. Digestion of the affinity-purified fraction with heparitinase I revealed a core protein of 63–69-kDa molecular mass, whereas digestion with chondroitinase ABC revealed a core protein of 100–110 kDa. The results suggest that expression of specific APP-binding proteoglycans may be an important step in the regulation of the neurite outgrowth-promoting activity of APP.

Item Type:	Refereed Article
Keywords:	Extracellular matrix; Neurite outgrowth; Heparin
Research Division:	Biomedical and Clinical Sciences
Research Group:	Neurosciences
Research Field:	Neurosciences not elsewhere classified
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Clinical health not elsewhere classified
UTAS Author:	Small, DH (Professor David Small)
ID Code:	75424
Year Published:	1995
Web of Science® Times Cited:	33
Deposited By:	Research Division
Deposited On:	2012-01-30
Last Modified:	2012-02-01
Downloads:	0