Properties of receptors for epidermal growth factor in detergent solution: Evidence for heterogeneous aggregated states

✍ Scribed by Linsley, Peter S. ;Fox, C. Fred

• Publisher: Wiley (John Wiley & Sons)
• Year: 1980
• Tongue: English
• Weight: 888 KB
• Volume: 14
• Category: Article
• ISSN: 0091-7419
• DOI: 10.1002/jss.400140409

✦ Synopsis

Abstract

Between 60% and 100% of epidermal growth factor (EGF) binding activity was recovered from membranes of the A431 human epidermoid carcinoma cell line treated with solutions containing the nonionic detergent Triton X‐100. Approximately half of the recovered binding activity was sedimented at low centrifugal forece and hence was operationally insoluble in nonionic detergent solution. Receptors in both the detergent‐soluble and ‐insoluble fractions displayed similar affinities for ^125^I‐EGF, and the values were in good agreement with those obtained for receptors in untreated membranes. The receptors in both fractions also formed identical direct linkage complexes with ^125^I‐EGF in similar yield, providing no evidence for partitioning of different molecular species of EGF receptors in the detergent‐soluble and ‐insoluble fractions.

Gel chromatography of the detergent‐soluble membrane fraction on Sepharose 6‐B revealed heterogeneity of ^125^I‐EGF binding activity; the smallest and most monodisperse peak of activity resolved by this technique was eluted at a Stokes radius of 95 Å. Operationally soluble ^125^I‐EGF binding activity also behaved heterogeneously during velocity sedimentation; more than half the activity sedimented more rapidly than the apparently monidisperse, 7S form. An average of less than half the nonionic detergent‐solubilized activity recovered from 10 independent membrane preparations behaved as an apparently monodisperse entity. Since a maximum of 60% of ^125^I‐EGF binding activity was operationally soluble, less than 25% of the total EGF binding activity was recovered in an apparently monodisperse form. The remaining 75% of the EGF receptors displayed a marked tendency to exist as aggregates in nonionic detergent solutions.