You can’t possibly get a good technology going

without an enormous number of failures. It’s a universal rule. If you look at bicycles, there were thousands of weird models built and tried before they found the one that really worked. You could never design a bicycle theoretically. Even now, after we’ve been building them for 100 years, it’s very difficult to understand just why a bicycle works – it’s even difficult to formulate it as a mathematical problem. But just by trial and error, we found out how to do it, and the error was essential.

– Freeman Dyson in a 1998 interview

Song of SecB

O lovely little nascent chain,
A protein soon you’ll be.
You’ll have to leave the ribosome
When it reads UAG.

Diffuse away! You cannot stay
But thanks to Brownian motion,
Before you know it you’re adrift
Upon the inner ocean.

I see you havea leader sequence
Tacked to your front end.
This means you’re going far from here,
My slowly folding friend.

If you will bind to all my sites,
I’ll change my conformation.
Then you’ll be well on your way
To membrane translocation.

Keep a lookout for SecA
For who I have affinity.
A dimer, tetramer and thou –
We three will form a trinity.

When we reach the membrane
I’ll dissociate.
But SecA will guide you safely
To your periplasmic fate.

One day when you’re far away
With ligands of your own,
Think of me, dear old SecB,
Your faithful chaperone.


– Virginia F. Smith,
published in the journal Trends in Biological Sciences, June 1998.