Foreign transmembrane peptides replacing the internal signal sequence of transferrin receptor allow its translocation and membrane binding

We have constructed three gene fusions that encode portions of a membrane protein, arginine permease, fused to a reporter domain, the cytoplasmic enzyme histidinol dehydrogenase (HD), located at the C-terminal end. These fusion proteins contain at least one of the internal signal sequences of arginine permease. When the fusion proteins were expressed in Saccharomyces cerevisiae and inserted into the endoplasmic reticulum (ER), two of the fusion proteins placed HD on the luminal side of the ER membrane, but only when a piece of DNA encoding a spacer protein segment was inserted into the fusion joint. The third fusion protein, with or without the spacer included, placed HD on the cytoplasmic side of the membrane. These results suggest that (i) sequences C-terminal to the internal signal sequence can inhibit membrane insertion and (ii) HD requires a preceding spacer segment to be translocated across the ER membrane.

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A Membrane Protease is Targeted to the Relict Plastid of Toxoplasma via an Internal Signal Sequence

Traffic ◽

10.1111/j.1600-0854.2007.00637.x ◽

2007 ◽

Vol 8 (11) ◽

pp. 1543-1553 ◽

Cited By ~ 41

Author(s):

Anuradha Karnataki ◽

Amy E. DeRocher ◽

Isabelle Coppens ◽

Jean E. Feagin ◽

Marilyn Parsons

Keyword(s):

Signal Sequence ◽

Internal Signal

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C-terminal sequences can inhibit the insertion of membrane proteins into the endoplasmic reticulum of Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.12.1.276-282.1992 ◽

1992 ◽

Vol 12 (1) ◽

pp. 276-282

Author(s):

N Green ◽

P Walter

Keyword(s):

Saccharomyces Cerevisiae ◽

Endoplasmic Reticulum ◽

Fusion Proteins ◽

Signal Sequence ◽

Dna Encoding ◽

Luminal Side ◽

Internal Signal ◽

Histidinol Dehydrogenase ◽

Arginine Permease ◽

Er Membrane

We have constructed three gene fusions that encode portions of a membrane protein, arginine permease, fused to a reporter domain, the cytoplasmic enzyme histidinol dehydrogenase (HD), located at the C-terminal end. These fusion proteins contain at least one of the internal signal sequences of arginine permease. When the fusion proteins were expressed in Saccharomyces cerevisiae and inserted into the endoplasmic reticulum (ER), two of the fusion proteins placed HD on the luminal side of the ER membrane, but only when a piece of DNA encoding a spacer protein segment was inserted into the fusion joint. The third fusion protein, with or without the spacer included, placed HD on the cytoplasmic side of the membrane. These results suggest that (i) sequences C-terminal to the internal signal sequence can inhibit membrane insertion and (ii) HD requires a preceding spacer segment to be translocated across the ER membrane.

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An ‘internal” signal sequence directs secretion and processing of proinsulin in bacteria

Nature ◽

10.1038/294176a0 ◽

1981 ◽

Vol 294 (5837) ◽

pp. 176-178 ◽

Cited By ~ 42

Author(s):

Karen Talmadge ◽

Jürgen Brosius ◽

Walter Gilbert

Keyword(s):

Signal Sequence ◽

Internal Signal

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Role of the human transferrin receptor cytoplasmic domain in endocytosis: localization of a specific signal sequence for internalization.

The Journal of Cell Biology ◽

10.1083/jcb.110.2.283 ◽

1990 ◽

Vol 110 (2) ◽

pp. 283-294 ◽

Cited By ~ 201

Author(s):

S Q Jing ◽

T Spencer ◽

K Miller ◽

C Hopkins ◽

I S Trowbridge

Keyword(s):

Amino Acid ◽

Transferrin Receptor ◽

High Efficiency ◽

Signal Sequence ◽

Cytoplasmic Domain ◽

Wild Type ◽

Human Transferrin ◽

Amino Acid Region ◽

Human Transferrin Receptor ◽

Mutant Receptors

Wild-type and mutant human transferrin receptors have been expressed in chicken embryo fibroblasts using a helper-independent retroviral vector. The internalization of mutant human transferrin receptors, in which all but four of the 61 amino acids of the cytoplasmic domain had been deleted, was greatly impaired. However, when expressed at high levels, such "tailless" mutant receptors could provide chicken embryo fibroblasts with sufficient iron from diferric human transferrin to support a normal rate of growth. As the rate of recycling of the mutant receptors was not significantly different from wild-type receptors, an estimate of relative internalization rates could be obtained from the distribution of receptors inside the cell and on the cell surface under steady-state conditions. This analysis and the results of iron uptake studies both indicate that the efficiency of internalization of tailless mutant receptors is approximately 10% that of wild-type receptors. Further studies of a series of mutant receptors with different regions of the cytoplasmic domain deleted suggested that residues within a 10-amino acid region (amino acids 19-28) of the human transferrin receptor cytoplasmic domain are required for efficient endocytosis. Insertion of this region into the cytoplasmic domain of the tailless mutant receptors restored high efficiency endocytosis. The only tyrosine residue (Tyr 20) in the cytoplasmic domain of the human transferrin receptor is found within this 10-amino acid region. A mutant receptor containing glycine instead of tyrosine at position 20 was estimated to be approximately 20% as active as the wild-type receptor. We conclude that the cytoplasmic domain of the transferrin receptor contains a specific signal sequence located within amino acid residues 19-28 that determines high efficiency endocytosis. Further, Tyr 20 is an important element of that sequence.

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