A new concept in polytopic membrane proteins following from the study of band 3 protein.
In the present communication, we introduce a novel concept in multispanning polytopic membrane proteins revealed by the study of the band 3 protein. The transmembrane domain of such proteins can be divided into three categories, that is, hydrophilic loops connecting transmembrane peptides (category 1), portions embedded by peptide-peptide interactions (category 2), and portions embedded by peptide-lipid interactions (category 3). Category 2 peptides of polytopic membrane proteins were found to stably reside in the lipid bilayer without peptide-lipid interactions that had been thought to be essential for transmembrane segments. Category 3 peptides are equivalent to single-spanning segments of bitopic membrane proteins. Three different experiments, namely proteolytic digestion, chemical modification of the band 3 protein, and cell free transcription and translation, were used to categorize the transmembrane peptides.
Hamasaki
N
N
Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Faculty of Medicine, Fukuoka, Japan. hamasaki@cclm.med.kyushu-u.ac.jp
Kuma
H
H
Ota
K
K
Sakaguchi
M
M
Mihara
K
K
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry*; D010450:Endopeptidases / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000145:classification; D008954:Models, Biological
D001457:Anion Exchange Protein 1, Erythrocyte; D008565:Membrane Proteins; D010450:Endopeptidases