Where is the location of heme in hemoglobin?

The amino acid sequences of the various globins are highly homologous to one another. Each has a highly helical secondary structure. Their globular teiary structures cause the exterior surfaces to be rich in polar (hydrophilic) amino acids that enhance solubility, and the interior to be lined with nonpolar groups, forming a hydrophobic pocket into which heme is inseed. Ref: Benz, E.J. (2012). Chapter 104. Disorders of Hemoglobin. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.