What is the mechanism for intracellular sorting of proteins via piggybacking?

[Monique]

What is the intracellular sorting mechanism called where a protein is transported by another protein?

Piggy back/ Piggyback

or

Piggy bag/ Piggybag?

 

[selfAdjoint]

Is this just an English word question?

Piggy-back is a child's term for being carried on someone's back. "Take me piggy-back daddy!". So it's universally used for any situation where one entity "carries" another.

 

[iansmith]

Protein that guide other protein are called chaperon. It probably called chaperoning

 

[Monique]

Originally posted by iansmith
Protein that guide other protein are called chaperon. It probably called chaperoning

You are right, but that is something else. Chaperone is not a mechanism for directing a protein to the lysosome or ER etc.

I guess selfAdjoint would be right, that it is piggy-back. I was confused, since both sound the same and I thought it would be a small bag carried on the back, so a piggy bag :P

Basically a protein has the signal sequence that allows it to be targeted to an organelle, a second protein lacks any signal sequence and thus is targeted by 'hopping on the back' of the other protein and hitching a ride to the appropriate organelle.

 

[Monique]

thanks for the help btw!

 

[iansmith]

You are right, but that is something else. Chaperone is not a mechanism for directing a protein to the lysosome or ER etc.

It is, this is the definition of a chaperone

http://www.geneed.com/glossary/c/index.html

A group of proteins that guide other proteins during their synthesis and assembly at the ribosome and their subsequent transport to their site of action

http://www.books.md/C/dic/chaperone.php

Cytoplasmic proteins of both prokaryotes and eukaryotes that bind to nascent or unfolded polypeptides and ensure correct folding or transport. Chaperone proteins do not covalently bind to their targets and do not form part of the finished product. Heat-shock proteins are an important sub set of chaperones. Three major families are recognised, the chaperonins (groEL and hsp60), the hsp70 family and the hsp90 family. Outside these major families are other proteins with similar functions including nucleoplasmin, secB and T-cell receptor associated protein.

 

[Monique]

Ok, so chaperone is the function of a protein that escorts another protein and the mechanism by which it works is piggy-back?

 

[iansmith]

Piggybacking appears to be more than a laymen word rather than the actual word use. Very article use piggybacking as the mecahnism for chaperoning.

From what I just read, piggybacking could be the transport of protein that are not newly synthesis and are staying in the cytoplasm. For example, protein that are activated after the signal transduction cascade and act in the on the DNA.

 

[Monique]

Originally posted by iansmith
Piggybacking appears to be more than a laymen word rather than the actual word use. Very article use piggybacking as the mecahnism for chaperoning.

From what I just read, piggybacking could be the transport of protein that are not newly synthesis and are staying in the cytoplasm. For example, protein that are activated after the signal transduction cascade and act in the on the DNA.

Oh, really. So chaperoning is the word to be used.. then I learned something new today since the word piggyback has been the only term that I heard :) no wonder I didn't find much on google. Thanks Ian.

 

[iansmith]

Originally posted by Monique
Oh, really. So chaperoning is the word to be used.. then I learned something new today since the word piggyback has been the only term that I heard :) no wonder I didn't find much on google. Thanks Ian.

Some biologist have this weird things, they create new word or expression for process that have been identify or are similar but not identical.

 

[rockind78]

Originally posted by Monique
What is the intracellular sorting mechanism called where a protein is transported by another protein?

Piggy back/ Piggyback

or

Piggy bag/ Piggybag?

According to my molecular prof, this is referred to as trafficing. Piggybacking is is specific "type" of trafficing. We just covered the topic this week or I would have chimed in sooner.

 

[Monique]

Good, so it is not the crazy dutch that are using the terminology :P you aren't in Holland, MI are you??

So yeah, piggybacking is when a protein hops on and hitches a ride. Probably when it doesn't have a signal sequence of its own, so it interacts with a protein that does and gets to its destination that way.

But apparently chaperoning is the correct term.

 

[eagleone]

Originally posted by Monique


But apparently chaperoning is the correct term.

Chaperoning could also imply folding and error fixing (not transporting directy). As I know chaperons basically help proteins in transporting through the membranes by defolding them on the entrance and properly folding them on exit, and keeping their proper 3D structure during the transport in the cell. Beside that family of chaperones include HSP molecules (mainly), and you know their purpose.

 

[Monique]

Yep, I know hsp

I also always thought that chaperoning just meant accompanying.

 

[eagleone]

Well, I think that you shouldn’t call all transport proteins and other carriers chaperones, I was thinking and remembered some paper I’ve wrote (including some HSP’s) and chaperons were strictly divided to:
e.g. HSP 70 - chaperons
e.g. HSP 60 + HSP 10 complex – chaperonines

And none of them is strictly a carrier, first one's are used for folding/defolding during the transport, and second for defolding missfolded, and prpoper folding.

So trafficin/piggybacking i maybe more matching :)