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Glucose binding enhances the papain susceptibility of the intracellular loop of the GLUT1 glucose transporter
Author(s) -
Asano Tomoichiro,
Katagiri Hideki,
Tsukuda Katsunori,
Lin Jiann-Liang,
Ishihara Hisamitsu,
Inukai Kouichi,
Yazaki Yoshio,
Oka Yoshitomo
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80038-i
Subject(s) - glut1 , intracellular , glucose transporter type 1 , papain , glucose transporter , biochemistry , transporter , gene isoform , chemistry , biology , enzyme , gene , endocrinology , insulin
Digestion of human GLUT1 protein in erythrocytes with 5 μg/ml papain for 5 min yielded several fragments. By using several site‐specific antibodies, two of these fragments containing the intracellular loop domain between M6 and M7 were demonstrated to be further digested by a prolonged incubation with papain. The addition of 0.2 M d ‐glucose enhanced this digestion between M6 and M7 by approximately 3.5‐fold, while the addition of 0.2 M d ‐sorbitol exhibited no effects. These results strongly suggest that d ‐glucose binding induces the conformational change of the intracellular loop domain between M6 and M7 of GLUT1 protein. Since the homology of the amino acid sequence was low in this intracellular domain among the five facilitative glucose transporter isoforms, this intracellular loop might contribute to the difference in their K m and V max values for glucose uptake.