Library · Molecule
Immunoglobulin G
Make it clearer
Immunoglobulin G, almost always written IgG, is one of the five types of immunoglobulin humans have. Immunoglobulin is another way of saying antibody: a protein that recognizes one specific invader. IgG is the one made mainly in the secondary immune response, that is, in the encounters that come after the first one.
Its shape explains a lot. It is a single unit with two identical antigen-binding sites, the points it uses to grab what it recognizes, and it also has a region called Fc that mediates its functions. It is a key with two identical teeth and a handle the rest of the team recognizes.
With that it can switch on the classical complement pathway, a group of blood proteins involved in defense. And it has one feature no other shares: it is the only one that crosses the placenta, which is why it is the most abundant antibody in a newborn.
It is not a single uniform molecule: it comes in four subclasses, numbered IgG1 through IgG4.
In brief
Immunoglobulin G, or IgG, is one of the five types of human immunoglobulin, and it is made mainly in the secondary immune response.
It is a single unit with two identical antigen-binding sites and an Fc region that mediates its functions.
A key with two identical teeth and a handle you can recognize.
It can activate the classical complement pathway, and it is the only one that crosses the placenta: it is the most abundant antibody in the newborn.
It comes in four subclasses: IgG1, IgG2, IgG3 and IgG4.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingImmunoglobulin, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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