A two-step recognition of signal sequences determines the translocation efficiency of proteins

Belin, Dominique; Bost, S.; Vassalli, Jean-Dominique; Strub, K.

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Title		A two-step recognition of signal sequences determines the translocation efficiency of proteins
Authors		Belin, Dominique Bost, S. Vassalli, Jean-Dominique Strub, K.
Published in		EMBO Journal. 1996, vol. 15, no. 3, p. 468-478
Abstract		The cytosolic and secreted, N-glycosylated, forms of plasminogen activator inhibitor-2 (PAI-2) are generated by facultative translocation. To study the molecular events that result in the bi-topological distribution of proteins, we determined in vitro the capacities of several signal sequences to bind the signal recognition particle (SRP) during targeting, and to promote vectorial transport of murine PAI-2 (mPAI-2). Interestingly, the six signal sequences we compared (mPAI-2 and three mutated derivatives thereof, ovalbumin and preprolactin) were found to have the differential activities in the two events. For example, the mPAI-2 signal sequence first binds SRP with moderate efficiency and secondly promotes the vectorial transport of only a fraction of the SRP-bound nascent chains. Our results provide evidence that the translocation efficiency of proteins can be controlled by the recognition of their signal sequences at two steps: during SRP-mediated targeting and during formation of a committed translocation complex. This second recognition may occur at several time points during the insertion/translocation step. In conclusion, signal sequences have a more complex structure than previously anticipated, allowing for multiple and independent interactions with the translocation machinery.
Keywords		Amino Acid Sequence — Animals — Base Sequence — Biological Transport, Active — Chickens — DNA/genetics — Endoplasmic Reticulum, Rough/metabolism — Female — Humans — Mice — Molecular Sequence Data — Mutagenesis, Site-Directed — Ovalbumin/genetics/metabolism — Plasminogen Activator Inhibitor 2/ genetics/ metabolism — Prolactin/genetics/metabolism — Protein Precursors/genetics/metabolism — Protein Sorting Signals/ genetics/ metabolism — Sequence Homology, Amino Acid — Serine Proteinase Inhibitors/ genetics/ metabolism — Signal Recognition Particle/metabolism
Identifiers		PMID: 8599930
Full text		Article - Limited access to UNIGE Other version: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC449965/pdf/emboj00003-0026.pdf
Structures		Faculté de médecine / Section de médecine clinique / Département de médecine
Citation (ISO format)		BELIN, Dominique et al. A two-step recognition of signal sequences determines the translocation efficiency of proteins. In: EMBO Journal, 1996, vol. 15, n° 3, p. 468-478. https://archive-ouverte.unige.ch/unige:8633