The polyguanidinium-ring-complex cation shield in the human red cell glucose transporter.
Widdas and Baker (1991) have described a possible structure and functioning of the human erythrocyte glucose transporter, based on its amino acid sequence. It was noted that eight positively charged side chains surrounded the proposed transfer cleft on the inside. These could form a ring shield which prevented the loss of K+ ions. Theoretical and model-making considerations point to this shield being made up of a polyguanidinium-ring-complex cation with eight (or ten) positive charges distributed over two identical rings of hydrogen bonds and normal linkages.
Widdas
W F
WF
Department of Biology (Physiology), Royal Holloway and Bedford New College, University of London, Egham, Surrey, Great Britain.
Baker
G F
GF
D000595:Amino Acid Sequence; D001665:Binding Sites; D001693:Biological Transport, Active; D004910:Erythrocyte Membrane / Q000737:chemistry*; D005947:Glucose / Q000378:metabolism; D006146:Guanidines / Q000737:chemistry*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000737:chemistry*
D006146:Guanidines; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D005947:Glucose