IgG2 vs IgG1-2-3 !

Mike Clark mrc7 at cam.ac.uk
Wed Nov 4 13:38:51 EST 1998

In article <3640021a.173779430 at news.club-internet.fr>, Emmanuel
<URL:mailto:nony at club-internet.fr> wrote:
> Hi,
> Does anyone around have an idea why IgG2 is different from
> other IgG ?

There are a number of papers which have looked at the amino acid
differences between the four human IgG subclasses and attempted to identify
residues responsible for functional differences. You might like to look at
a recent review of mine

Clark, M (1997), Chemical Immunology 65, 88-110 Antibody Engineering: IgG
Effector Mechanisms

> I seems not to cross the placenta for instance.

Yes I have seen reports to this in several textbooks and I have also seen
other measurements which seem to show that IgG2 does cross the placenta.
Interestingly IgG2 shows an extended half-life like IgG1 and IgG4 so it
presumably binds quite well to the Brambell receptor (otherwise known as
FcRn and thought to be responsible for transport across the placenta) In
addition there are no residues at the proposed binding site for FcRn on IgG
that would appear to be candidates for a failure of IgG2 to be transported.
Some have suggested that there is a polymorphism in binding to another
receptor such as FcgRIIa which is responsible for this difference.

> Is there any differences in primary structure and/or post translational
> modifications such as glycosylation ?

Yes there are differences in amino acid sequence and structure.
Glycosylation is another possible difference because this can be influenced
by the amino acid sequence around the conserved glycosylation sites (see
articles by Roy Jefferis and also by Sherie Morrison

> Any nice books/reviews regarding IgG structures / properties ?

You could also take a look at my Antibody Structure/Function Web site which
has references and some links to other sites (see below)


> Thank you !
> Emmanuel Nony.
> nony at club-internet.fr

Mike Clark
 o/ \\    //            ||  ,_ o   M.R. Clark, PhD. Division of Immunology
<\__,\\  //   __o       || /  /\,  Cambridge University, Dept. Pathology
 ">    ||   _`\<,_    //  \\ \> |  Tennis Court Rd., Cambridge CB2 1QP
  `    ||  (_)/ (_)  //    \\ \_   Tel.+44 1223 333705  Fax.+44 1223 333875

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