Imaging LDL receptor oligomerization during endocytosis using a co-internalization assay
Alice Ting and Peng Zou
ACS Chem. Biol.,
DOI: 10.1021/cb100361k

Methods to probe receptor oligomerization are useful to understand the molecular mechanisms of receptor signaling. Here we report a fluorescence imaging method to determine receptor oligomerization state in living cells during endocytic internalization. The wild-type receptor is co-expressed with an internalization-defective mutant, and the internalization kinetics of each is independently monitored. If the receptor internalizes as an oligomer, then the wild-type and mutant isoforms will mutually influence each others' trafficking properties, causing co-internalization of the mutant, or co-retention of the wild-type at the cell surface. Using this approach, we found that the low density lipoprotein (LDL) receptor internalizes as an oligomer into cells, both in the presence and absence of LDL ligand. The internalization kinetics of the wild-type receptor is not changed by LDL binding. We also found that the oligomerization domain of the LDL receptor is located in its cytoplasmic tail.

Professor Dietmar Seyferth’s academic autobiography entitled “Looking Back on Happy Years in Chemistry” has been published in a special issue of Organometallics, November 8, 2010, Volume 29, Number 21. The special issue was dedicated to Dietmar on the occasion of his retirement as editor of the journal. It contained approximately 125 contributions from all over the world.

Professor Seyferth was the first Editor-in-Chief of Organometallics, appointed to the position in 1981, and transitioning to Editor Emeritus during 2010. He will be honored as “Founding Editor” on the journal masthead starting in 2011.