Amino Acid Sequence of Insulin


Here's a chart of the variations in amino acid sequence on the A and B chains of different species. (from W. Ganong, Review of medical physiology 1989, and Canine and Feline Endocrinology and
Reproduction).  You can see that dog and pork insulin have identical amino acid sequences.  Cat and human insulin vary in all 4 positions, whereas cat and beef insulin vary in one position. 

Species Amino Acid Chain and Position
A #8 A #10  A #18 B #30
porcine (pork), dog Thr  Ile Asn Ala
human Thr  Ile Asn Thr
cat Ala Val His Ala
bovine (beef) Ala Val Asn Ala

Ala = alanine
His = histidine
Ile = isoleucine
Thr = threonine
Val = valine

The structure of bovine insulin, showing the amino acid sequence of the two chains and the cross-linkages.  The bold positions are where substitutions usually occur.  From Lehninger: Principles of Biochemistry.  1982.  Pg. 134 Figure 6-11. 


  • Insulin structure information and image from Lehninger: Principles of Biochemistry.  Albert L. Lehninger, Editor.  Worth publishers, Inc. 1982.
  • Review of Medical Physiology Fourteenth Edition, 1989.  William F. Ganong, Editor.  Appleton & Lange, Publishers.

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Updated November 2000
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