Abstract:
:We have developed a method for conjugating low density lipoproteins (LDL) with colloidal gold. Conjugation, complete after 1 min, occurs by electrostatic adsorption of the LDL to the negatively charged gold particle. Each conjugate consists of approximately eight biologically active LDL molecules clustered around a central 19-nm gold granule. Acidic (pH 4), alkaline (pH 9), or high ionic (600 milliosmolar NaCl) environments do not dissociate the conjugate. Colloidal gold is an electron-dense, nondegradable marker that is easily identified within the cell and serves as a valuable probe for studying receptor binding and endocytosis. By using a modified method of ruthenium red staining, the LDL molecules of the conjugate can be directly visualized when they are bound to the cell surface receptor. Receptor binding (4 degrees C) of the conjugate by cultured human fibroblasts reveals that the gold granule is positioned 18-21 nm from the coated pit region of the membrane. This distance, similar to the diameter of LDL, suggests concomitant internalization of the receptor during vesicular endocytosis and early lysosomal incorporation (10 min at 37 degrees C). Continued internalization (30-60 min at 37 degrees C) results in the formation of free pools of gold within the lysosome.
journal_name
Proc Natl Acad Sci U S Aauthors
Handley DA,Arbeeny CM,Witte LD,Chien Sdoi
10.1073/pnas.78.1.368subject
Has Abstractpub_date
1981-01-01 00:00:00pages
368-71issue
1eissn
0027-8424issn
1091-6490journal_volume
78pub_type
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