are there any proteins < 1 kD?

[Michael Levin]

   Are there any proteins or protein families less than 1 kD in size? I'm
especially interested in ones which may have an interesting role in some
process (regulation, development, etc.). Please send any ideas to
mlevin at fas.harvard.edu (or, if there's some database that one can search
with this sort of criteria in mind, I'd be very grateful to know). 
Thanks!

Mike Levin