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Related Experiment Video

Updated: Jul 7, 2026

Isolation, Expansion, and Adipogenic Induction of CD34+CD31+ Endothelial Cells from Human Omental and Subcutaneous Adipose Tissue

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Published on: July 17, 2018

Localization of the insulin receptor in caveolae of adipocyte plasma membrane.

J Gustavsson¹, S Parpal, M Karlsson

¹Department of Cell Biology, Department of Medical Microbiology, Faculty of Health Sciences, Linköping University, S-58185 Linköping, Sweden.

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology

|November 2, 1999

Summary

Insulin receptors are located in caveolae microdomains of adipocyte plasma membranes. Cholesterol reduction in caveolae disrupts insulin receptor signaling, highlighting the importance of this cellular environment.

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Area of Science:

Cell Biology
Molecular Endocrinology
Membrane Biology

Background:

The insulin receptor (INSR) is a crucial transmembrane protein mediating insulin's effects.
Cellular signaling relies on the precise localization and function of receptors within the plasma membrane.
Caveolae are specialized microdomains within the plasma membrane involved in cellular signaling and transport.

Purpose of the Study:

To investigate the localization and signaling role of insulin receptors within adipocyte plasma membrane caveolae.
To determine the dependence of insulin receptor signaling on the caveolae microenvironment, particularly cholesterol content.

Main Methods:

Immunogold electron microscopy and immunofluorescence microscopy to visualize INSR and caveolin localization.
Biochemical fractionation to isolate caveolae-enriched membrane fractions.
Cholesterol manipulation using beta-cyclodextrin and cholesterol oxidase to assess signaling effects.
Measurement of insulin-induced protein phosphorylation and glucose transport.

Main Results:

Insulin receptors were found to be localized exclusively within caveolae of adipocyte plasma membranes, colocalizing with caveolin.
Cholesterol depletion using beta-cyclodextrin or cholesterol oxidase significantly attenuated insulin receptor signaling, including protein phosphorylation and glucose transport.
Restoration of cholesterol levels or spontaneous recovery re-established insulin signaling, and beta-cyclodextrin treatment disrupted caveolae structure.
Insulin stimulation enhanced tyrosine phosphorylation of INSR within isolated caveolae, confirming their functional activity in this microdomain.

Conclusions:

Insulin receptors are specifically localized to caveolae in adipocyte plasma membranes.
Insulin receptor signaling is dependent on the integrity and cholesterol content of the caveolae microenvironment.
Caveolae serve as critical signaling platforms for the insulin receptor in adipocytes.