**********************************
* Somatomedin B domain signature *
**********************************

Somatomedin B, a serum  factor of  unknown  function, is  a  cysteine-rich  45
residues  peptide  which  is  proteolytically   derived  from  the  N-terminal
extremity  of the cell-substrate adhesion protein vitronectin [1]. Somatomedin
B-like domains are also found [2] in the following proteins:

 - Plasma-cell membrane glycoprotein PC-1.  PC-1, a  protein  with  nucleotide
   pyrophosphatase (EC 3.6.1.9)  and alkaline phosphodiesterase I (EC 3.1.4.1)
   activities [3], is a  type-II  membrane protein of about 870 residues.  PC1
   consists of a short cytoplasmic  domain, followed by a transmembrane region
   and a large extracellular domain.  Two  tandem  copies  of a  somatomedin B
   domain are present in the N-terminal extremity of the extracellular domain.
 - Placental protein 11 (PP11).  PP11  is  a  placental protein  that seems to
   possess an amidolytic activity.  A  copy  of  the  somatomedin B  domain is
   present at the N-terminal extremity.

As shown in  the  following  schematic  representation  below  there are eight
conserved cysteines  in  the  somatomedin B  domain  and they are probably all
involved in disulfide bonds.

         xxCxxxxxxCxxxxxxxxxCxCxxxCxxxxxCCxxxxxCxxxxx
                            ********************

'C': conserved cysteine probably involved in a disulfide bond.
'*': position of the pattern.

-Consensus pattern: C-x-C-x(3)-C-x(5)-C-C-x-[DN]-[FY]-x(3)-C
-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: Jenne D.
                                djenne@clsuni51.bitnet

-Last update: December 1991 / First entry.

[ 1] Jenne D., Stanley K.K.
     Biochemistry 26:6735-6742(1987).
[ 2] Jenne D.
     Biochem. Biophys. Res. Commun. 176:1000-1006(1991).
[ 3] Rebbe N.F., Tong B.D., Finley E.M., Hickman S.
     Proc. Natl. Acad. Sci. U.S.A. 88:5192-5196(1991).