{PDOC00216}
{PS00243; INTEGRIN_BETA}
{BEGIN}
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* Integrins beta chain cysteine-rich domain signature *
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Integrins [1,2] are a large family of cell surface receptors that mediate cell
to cell as well as cell to matrix adhesion. Some integrins recognize the R-G-D
sequence in their extracellular matrix protein ligand. Structurally, integrins
consist of a dimer of an alpha and a beta chain.  Each  subunit  has  a  large
N-terminal extracellular domain followed by a transmembrane domain and a short
C-terminal cytoplasmic  region. Some receptors share a common beta chain while
having different  alpha chains.  The  sequence  of  a number of different beta
chains has been determined and are listed below:

 - Integrin beta-1, which  associates with alpha-1 to form a laminin receptor,
   with alpha-2 to form a  collagen receptor, with  alpha-4  to  interact with
   VCAM-1, with alpha-5 to form a fibronectin receptor, and with alpha-8.
 - Integrin beta-2, which  associates with alpha-L (LFA-1)  to  interact  with
   ICAM-1, and with alpha-M (MAC-1) or alpha-X  (p150,95) to form the receptor
   for the iC3b fragment of the third complement component.
 - Integrin beta-3, which associates with alpha-IIB  to  form  a  receptor for
   fibrinogen,  fibronectin,  vitronectin and VWF, and with alpha-V  to form a
   vitronectin receptor.
 - Integrin beta-4, which associates with alpha-6.
 - Integrin beta-5, which associates with alpha-V.
 - Integrin beta-6 [3].
 - Integrin beta-7 [4].
 - Integrin beta-8, which associates with alpha-V [5].
 - The Drosophila myospheroid protein, a probable integrin beta chain.

All the integrin beta chains contain four repeats of a forty amino acid region
in the C-terminal extremity of their extracellular domain. Each of the repeats
contains eight  cysteines.   We have developed a pattern from a section of the
repeated region that includes five of these conserved cysteines.

-Consensus pattern: C-x-[GNQ]-x(1,3)-G-x-C-x-C-x(2)-C-x-C
                    [The 5 C's may be involved in disulfide bonds]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: The pattern will not pick up the first of the four repeats, the spacing
 of the cysteine residues being different in that repeat.

-Last update: May 2004 / Text revised.

[ 1] Hynes R.O.
     "Integrins: a family of cell surface receptors."
     Cell 48:549-554(1987).
     PubMed=3028640
[ 2] Albelda S.M., Buck C.A.
     "Integrins and other cell adhesion molecules."
     FASEB J. 4:2868-2880(1990).
     PubMed=2199285
[ 3] Sheppard D., Rozzo C., Starr L., Quaranta V., Erle D.J., Pytela R.
     "Complete amino acid sequence of a novel integrin beta subunit (beta
     6) identified in epithelial cells using the polymerase chain
     reaction."
     J. Biol. Chem. 265:11502-11507(1990).
     PubMed=2365683
[ 4] Erle D.J., Rueegg C., Sheppard D., Pytela R.
     "Complete amino acid sequence of an integrin beta subunit (beta 7)
     identified in leukocytes."
     J. Biol. Chem. 266:11009-11016(1991).
     PubMed=2040616
[ 5] Moyle M., Napier M.A., McLean J.W.
     "Cloning and expression of a divergent integrin subunit beta 8."
     J. Biol. Chem. 266:19650-19658(1991).
     PubMed=1918072

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