Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2017 May 1;216(5):1357–1369. doi: 10.1083/jcb.201609022

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2017 Chatzi et al.

This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).

PMC Copyright notice

Figure 2. — MTSs are essential for protein secretion. (A) Representative, in vitro, SecA-dependent translocation assays of proPhoA(1–122)M1,2 compared with proPhoA(1–122) (top) and proPhoA(350–471)M8-11 compared with proPhoA(350–471) (bottom) into the lumen of SecYEG containing inverted membrane vesicles; n = 3. 5% of the input is indicated. (B) In vivo secretion of proYncJ-PhoA (left) and proYncJ(noMTS)-PhoA (right) was compared with that of proPhoA (considered as 100%) under identical conditions (MC4100 cells; OD₆₀₀ = 0.2; 0.002% wt/vol arabinose; 30min; 30°C). In all cases, the measured PhoA enzymatic activity (Gouridis et al., 2009) was normalized to the amount of PhoA or fusion-PhoA protein produced. This provided a means to quantitate the in vivo secretion of all three proteins. The alkaline phosphatase units per microgram PhoA for cells expressing proPhoA was considered 100%; proYncJ-PhoA and proYncJ(noMTS)-PhoA values were expressed as a percentage of this value. n = 5. Values are expressed as means ± SEM. (C) Schematic summary of requirements for preprotein targeting and translocation (as indicated). Preproteins are bivalent ligands with distinct binding sites on SecA. Targeting to the translocase is efficiently achieved by either targeting element, the signal peptide (middle) or one/more MTSs (bottom), independently. However, preprotein translocation requires binding of both (top).