MyJournals Home  

RSS FeedsCD16a with oligomannose-type N-glycans is the only “low-affinity” Fc {gamma} receptor that binds the IgG crystallizable fragment with high affinity in vitro [Immunology] (Journal of Biological Chemistry)

 
 

27 october 2018 23:03:59

 
CD16a with oligomannose-type N-glycans is the only “low-affinity” Fc {gamma} receptor that binds the IgG crystallizable fragment with high affinity in vitro [Immunology] (Journal of Biological Chemistry)
 




Fc ? receptors (Fc?Rs) bind circulating IgG (IgG1) at the surface of leukocytes. Antibodies clustered at the surface of a targeted particle trigger a protective immune response through activating Fc?Rs. Three recent reports indicate that the composition of the asparagine-linked carbohydrate chains (N-glycans) of Fc?RIIIa/CD16a impacted IgG1-binding affinity. Here we determined how N-glycan composition affected the affinity of the `low-affinity` Fc?Rs for six homogeneous IgG1 Fc N-glycoforms (G0, G0F, G2, G2F, A2G2, and A2G2F). Surprisingly, CD16a with oligomannose N-glycans bound to IgG1 Fc (A2G2) with a KD = 1.0 0.1 nm. This affinity represents a 51-fold increase over the affinity measured for CD16a with complex-type N-glycans (51 8 nm) and is comparable with the affinity of Fc?RI/CD64, the sole `high-affinity` Fc?R. CD16a N-glycan composition accounted for increases in binding affinity for the other IgG1 Fc glycoforms tested (10-50-fold). This remarkable sensitivity could only be eliminated by preventing glycosylation at Asn162 with an Asn-to-Gln mutation; mutations at the four other N-glycosylation sites preserved tighter binding in the Man5 glycoform. None of the other low-affinity Fc?Rs showed more than a 3.1-fold increase upon modifying the receptor N-glycan composition, including CD16b, which differs from CD16a by only four amino acid residues. This result indicates that CD16a is unique among the low-affinity Fc?Rs, and modifying only the glycan composition of both the IgG1 Fc ligand and receptor provides a 400-fold range in affinities.


Del.icio.us Digg Facebook Google StumbleUpon Twitter
 
32 viewsCategory: Biochemistry
 
CatSper channels are regulated by protein kinase A [Developmental Biology] (Journal of Biological Chemistry)
Phosphatase activity of small C-terminal domain phosphatase 1 (SCP1) controls the stability of the key neuronal regulator RE1-silencing transcription factor (REST) [Gene Regulation] (Journal of Biological Chemistry)
 
 
blog comments powered by Disqus


MyJournals.org
The latest issues of all your favorite science journals on one page

Username:
Password:

Register | Retrieve

Search:

Biochemistry

Use these buttons to bookmark us:
Del.icio.us Digg Facebook Google StumbleUpon Twitter


Valid HTML 4.01 Transitional
Copyright © 2008 - 2019 Indigonet Services B.V.. Contact: Tim Hulsen. Read here our privacy notice.
Other websites of Indigonet Services B.V.: Nieuws Vacatures News Tweets Travel Photos Nachrichten Indigonet Finances Leer Mandarijn