Question

Glycophorins are red blood cell membrane glycoproteins that bear important blood-group antigens. Shown below is the primary sequence for glycophorin B which possesses a single transmembrane segment. (Blanchard et al., J. Biol. Chem. 262 (1987) 5808). Identify the likely ‘transmembrane’ segment (provide residue number range) and justify your selection.

Leu Ser Thr Thr Glu Val Ala Met His Thr Ser Thr Ser Ser Ser Val Thr Lys Ser Tyr 20

Ile Ser Ser Gln Thr Asn Gly Glu Met Gly Gln Leu Val His Arg Phe Thr Val Pro Ala 40

Pro Val Val Ile Ile Leu Ile Ile Leu Ser Val Met Ala Gly Ile Ile Gly Thr Ile Leu 60

Leu Ile Ser Tyr Ser Ile Arg Arg Leu Ile Lys 71