***********************
* ZP domain signature *
***********************

A domain of about 260 amino acid residues  has been recognized [1] in a number
of receptor-like eukaryotic glycoproteins; these proteins are listed below.

 - Sperm receptor proteins ZP2 and ZP3.  Along  with protein ZP1, proteins ZP2
   and ZP3 are responsible for sperm-adhesion to the zona pellucida. ZP3 first
   binds to specific sperm proteins, thus  mediating  sperm  contacts with the
   oocyte. ZP2 acts a second sperm receptor reinforcing the interactions.  ZP1
   cross-links the polymers formed by ZP2 and ZP3.
 - Glycoprotein GP2,  the  major  component  of  pancreatic  secretory granule
   membranes.
 - TGF-beta receptor type III (also  known  as betaglycan).  This protein is a
   proteoglycan that binds to TGF-beta and that could be involved in capturing
   and retaining TGF-beta for presentation to the signalling receptors.
 - Uromodulin (also known as Tamm-Horsfall urinary glycoprotein). The function
   of this protein, which is the most abundant  protein in human urine, is not
   yet clear.

All of the above proteins are mosaic proteins composed of various domains, but
they  all  consist  of a  large  extracellular region  followed  by  either  a
transmembrane region  and a very short cytoplasmic region or  by a GPI-anchor.
The domain which is common to these proteins, and that we call 'ZP', is  found
in the C-terminal section of the extracellular region.  The ZP domain contains
eight conserved cysteines that are probably involved in disulfide bonds.

As a signature pattern for this  domain  we  selected a region, in the central
part of the ZP domain, that contains two of the conserved cysteines.

-Consensus pattern: [LIVMFYW]-x(7)-[STADN]-x(3)-[LIVMFYW]-x-[LIVMFYW]-x-
                    [LIVMFYW]-x(2)-C-[LIVMFYW]-x-[ST]-[PS]-x(2,4)-[DN]-x-
                    [STADN]-x(6)-[LIVM](2)-x(3,4)-C
                    [The two C's are probably involved in disulfide bonds]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Expert(s) to contact by email: Bork P.
                                bork@embl-heidelberg.de

-Last update: June 1992 / First entry.

[ 1] Bork P., Sander C.
     FEBS Lett. 300:237-240(1992).