Abstract

Caveolin-1 is a major component protein of the caveolae—a type of flask shaped, 50-100 nm, nonclathrin-coated, microdomain present in the plasma membrane of most mammalian cells. Caveolin-1 functions as a scaffolding protein to organize and concentrate signaling molecules within the caveolae, which may be associated with its unique physicochemical properties including oligomerization, acquisition of detergent insolubility, and association with cholesterol. Here we demonstrate that caveolin-1 is detected in all brain areas examined and recovered in both detergent-soluble and -insoluble fractions. Surprisingly, the recovered molecules from the two different fractions share a similar molecular size ranging from 200 to 2,000 kDa, indicated by gel filtration. Furthermore, both soluble and insoluble caveolin-1 molecules generate a proteinase K (PK)-resistant C-terminal core fragment upon the PK-treatment, by removing ˜36 amino acids from the N-terminus of the protein. Although it recognizes caveolin-1 from A431 cell lysate, an antibody against the C-terminus of caveolin-1 fails to detect the brain protein by Western blotting, suggesting that the epitope in the brain caveolin-1 is concealed. No significant differences in the physicochemical properties of caveolin-1 between uninfected and prion-infected brains are observed.

Highlights

  • Caveolae are invaginations of the plasma membrane with a diameter of 60-80 nm, formed by the polymerization of caveolin-1 and a subset of lipid-raft components, including cholesterol and sphingolipids [1]

  • Using Western blot analysis, we first investigated the distribution of caveolin-1 in different brain areas in normal individuals and patients with sporadic CreutzfeldtJakob disease, the most common form of human prion disease

  • There were no significant differences in caveolin-1 levels between non-CJD and sporadic CreutzfeldtJakob disease (sCJD) patients (Figure 1B)

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Summary

Introduction

Caveolae are invaginations of the plasma membrane with a diameter of 60-80 nm, formed by the polymerization of caveolin-1 and a subset of lipid-raft components, including cholesterol and sphingolipids [1]. Caveolae have been implicated in endocytosis, transcytosis, calcium signaling and numerous other signal transduction events in several types of cells including neurons. Caveolin-1 is the only known protein component of the caveolae. It has an unusual membrane topology with N and C termini in the cytoplasm and a long putative hairpin intramembrane domain. Oligomerization and association of caveolin-1 with cholesterol-rich lipid-raft domains are involved in the formation of caveola [1]. Caveolin-1 binds 1 to 2 cholesterol molecules and is palmitoylated in the C-terminal regions

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