id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-315316-w7cn9iqp	Earnest, James T.	The tetraspanin CD9 facilitates MERS-coronavirus entry by scaffolding host cell receptors and proteases	2017-07-31		.txt	text/plain	7820	418	48	Infection by enveloped coronaviruses (CoVs) initiates with viral spike (S) proteins binding to cellular receptors, and is followed by proteolytic cleavage of receptor-bound S proteins, which prompts S protein-mediated virus-cell membrane fusion. Using knockout cell lines, we found that the tetraspanin CD9, but not the tetraspanin CD81, formed cell-surface complexes of dipeptidyl peptidase 4 (DPP4), the MERS-CoV receptor, and the type II transmembrane serine protease (TTSP) member TMPRSS2, a CoV-activating protease. TTSP family members, most notably the transmembrane protease serine type 2 (TMPRSS2), can cleave CoV fusion glycoproteins (termed spike [S] proteins), into unlocked, fusion-catalyzing forms [8, 9, 11] at the cell surface and facilitate a rapid, "early" entry. Even antibodies binding to CD81 suppressed MERS S-mediated entry [14] , indicating that several tetraspanins, including those that are not required per se for clustering hDPP4 and TMPRSS2, organize into cell-surface "webs" [15] and enclose the CoV entry factors.	./cache/cord-315316-w7cn9iqp.txt	./txt/cord-315316-w7cn9iqp.txt