Pathway · 3 proteins
Protein export
Proteins of this group that KEGG places on its “Protein export” map for Aquifex aeolicus.
How it works
This map covers how proteins are moved into and across the membrane. The proteins here are YidC, which inserts membrane proteins, and the two signal peptidases that cut off the targeting signals of exported proteins and lipoproteins.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Membrane protein insertase YidC | — | — | — | 502 | Step named |
| Lipoprotein signal peptidase | 3.4.23.36 | Release of signal peptides from bacterial membrane prolipoproteins. Hydrolyzes -Xaa-Yaa-Zaa-|-(S,diacylglyceryl)Cys-, in which Xaa is hydrophobic (preferably Leu), and Yaa (Ala or Ser) and Zaa (Gly or Ala) have small, neutral side chains. | — | 167 | Step named |
| Signal peptidase I | 3.4.21.89 | Cleavage of hydrophobic, N-terminal signal or leader sequences from secreted and periplasmic proteins. | — | 256 | Step named |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Protein translocase subunit SecYHome: Protein translocation | — | — | — | 429 | Step named |
| Protein-export membrane protein SecGHome: Protein translocation | — | — | — | 100 | Step named |
| Sec translocon accessory complex subunit YajCHome: Protein translocation | — | — | — | 102 | Step named |
| Sec-independent protein translocase protein TatCHome: Protein translocation | — | — | — | 240 | Step named |
| Protein translocase subunit SecFHome: Protein translocation | — | — | — | 288 | Step named |
| Signal recognition particle proteinHome: Protein targeting | 3.6.5.4 | GTP + H2O = GDP + phosphate + H(+) | — | 454 | Step named |
| Protein translocase subunit SecAHome: Protein translocation | 7.4.2.8 | ATP + H2O + cellular proteinSide 1 = ADP + phosphate + cellular proteinSide 2. | — | 984 | Step named |
| Signal recognition particle receptor FtsYHome: Protein targeting | 3.6.5.4 | GTP + H2O = GDP + phosphate + H(+) | — | 461 | Step named |
| Protein translocase subunit SecDHome: Protein translocation | — | — | — | 501 | Step named |
Origins
How could proteins be sent out of the cell before export systems existed?
The books searched discuss protein export only in present-day cells.
Exported proteins carry a signal at their start that is cut off by a signal peptidase once the protein has crossed. The signal, the channel and the cutting enzyme must all be present for export to work.
Rana argues that information-rich molecules and the systems built on them are the strongest pointers to a designer, because their information is crafted, not merely present.
From the books: Rana, The Cell's Design.
The wider question for this part of the cell: origins for building proteins and folding them.
Sources
- KEGG map aae03060 (enzymes of this organism highlighted)
Other pathways in this group: Ribosomal subunits · Translation interface · RNA maturation · Translation cycle · Protein translocation · Protein turnover · Folding and stabilization · Recycling and rescue · Early folding support · Protein targeting · Ribosome · Not yet placed in a pathway