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Journal Article

A tetrameric complex of membrane proteins in the endoplasmic reticulum.


Görlich,  D.
Department of Cellular Logistics, MPI for biophysical chemistry, Max Planck Society;

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Hartmann, E., Görlich, D., Kostka, S., Otto, A., Kraft, R., Knespel, S., et al. (1993). A tetrameric complex of membrane proteins in the endoplasmic reticulum. European Journal of Biochemistry, 214(2), 375-381. doi:10.1111/j.1432-1033.1993.tb17933.x.

Cite as: http://hdl.handle.net/11858/00-001M-0000-0015-3BD2-F
The translocation site (translocon), at which nascent polypeptides pass through the endoplasmic reticulum membrane, contains a component previously called ‘signal sequence receptor’ that is now renamed as ‘translocon-associated protein’ (TRAP). Two glycosylated subunits of the TRAP complex have been identified before (α and β subunits). We now show that the TRAP complex is actually comprised of four membrane proteins (α, β, γ, δ), present in a stoichiometric relation, which are genuine neighbours in intact microsomes. The amino acid sequences of the additional, non-glycosylated subunits were deduced from cloning of the corresponding cDNAs. The δ subunit spans the membrane only once and has its major portion, containing a disulfide bridge, at the lumenal side. The γ subunit is predicted to span the membrane four times.