QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lovati, M. R. Articles by Sirtori, C. R. Search for Related Content PubMed PubMed Citation Articles by Lovati, M. R. Articles by Sirtori, C. R.

7S Globulin from Soybean Is Metabolized in Human Cell Cultures by a Specific Uptake and Degradation System¹

Institute of Pharmacological Sciences, University of Milan, 20133 Milan, Italy

We examined the biological fate of 7S globulin from soybean in a hepatoma cell line (Hep G2) and in human skin fibroblasts (HSF) to gain new insights into the 7S globulin cell process, the final effect of which is an enhanced expression of the LDL-receptor. The ability of 7S globulin to bind and to be internalized and degraded by both cell types was investigated under different experimental conditions. In all cases, specific uptake (binding + internalization) and degradation of ¹²⁵I-7S globulin were curvilinear functions of substrate concentration at 37°C. The two processes were saturated at around 80 mg/L, a concentration at which an up-regulation of LDL-receptor was previously reported. The specific uptake of ¹²⁵I-7S globulin at 37°C was a curvilinear function of time, and achieved equilibrium after 6 and 12 h in HSF and Hep G2 cells, respectively. Binding experiments, conducted at 4°C in Hep G2 cells, showed a specific and saturable association of 7S globulin to the cell membrane. Linear Scatchard analysis demonstrated a single population of binding sites. The amount of 7S globulin bound at saturation (B_max) was about 2.73 mg/L, with an apparent K_d of 21 µmol/L, assuming 175 kDa as the 7S globulin molecular weight. SDS-PAGE of Hep G2 membrane proteins incubated with ¹²⁵I-7S globulin revealed a specific interaction of 7S globulin with a cell protein component with molecular weight between 14 and 21 kDa. Further studies are needed to ascertain whether this interaction is directly or indirectly related to the observed stimulation of the LDL-receptor.

KEY WORDS: • 7S, 11S soybean globulins • Hep G2 cells • human skin fibroblasts • cholesterol reduction

¹ The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC section 1734 solely to indicate this fact.

² To whom correspondence should be addressed.

Manuscript received 14 December 1995. Revision accepted 29 July 1996.