What is the significance of letter A in immunoglobulinA?

What are the significance of other letters D, M , G, E in diffeternt types of antibodies?


1 Answer 1


The letter suffix in the name or abbreviation of an immunoglobulin specifies which type of "heavy chain" the immunoglobin contains. The heavy chain is the large polypeptide (amino acid chain) found in the antibody. In mammals there are five different classes or types of heavy chains, and these types are given Greek letters to differentiate them.

As Wikipedia says,

The different suffixes of the antibody isotypes denote the different types of heavy chains the antibody contains, with each heavy chain class named alphabetically: α, γ, δ, ε, and μ. This gives rise to IgA, IgG, IgD, IgE, and IgM, respectively.

Thus the Ig suffix letter is the Roman letter corresponding to the equivalent Greek letter of the heavy chain that Ig contains.

  • $\begingroup$ Does the heavy chain has name A or it's an abbreviation? $\endgroup$
    – JM97
    Apr 24, 2016 at 9:04
  • $\begingroup$ For igA, the heavy chain is of type α (Greek letter alpha, not Roman A). $\endgroup$
    – mgkrebbs
    Apr 24, 2016 at 14:22
  • $\begingroup$ @mgkrebbs whoever named these proteins named the chains with similar greek letters for compatibility. I don't think they were named based on the chains they have. See the linked post. I think the answer there explains the possible origin of these names. $\endgroup$
    Apr 25, 2016 at 6:54

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