{PDOC51115}
{PS51115; LAMININ_IVA}
{PS51116; LAMININ_IVB}
{BEGIN}
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* Laminin IV domain profiles *
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Laminin  is  a  large  molecular  weight glycoprotein present only in basement
membranes  in  almost  every  animal  tissue.  Each  laminin is a heterotrimer
assembled from alpha, beta and gamma chain subunits, secreted and incorporated
into  cell-associated  extracellular matrices. The laminins can self-assemble,
bind  to  other  matrix  macromolecules,  and  have  unique  and  shared  cell
interactions mediated by integrins, dystroglycan, and other receptors. Through
these  interactions,  laminins  critically contribute to cell differentiation,
shape  and movement, maintenance of tissue phenotypes, and promotion of tissue
survival [1,2].

The   different   laminin   chains  share  a  600-residue  domain  I/II  which
oligomerizes  into  a  rod-like  coiled-coil structure forming the long arm of
laminins.  The  N-terminal short arms consist of rod-like elements (domain III
and  V)  formed by tandem arrays of laminin-type EGF modules (see <PDOC00961>)
and   several   globular   domains:   domains   IV   and  domain  VI  (laminin
N-terminal) (see  <PDOC51117>). All  alpha  chains share a unique C-terminal G
domain which consists of five laminin G modules (see <PDOC50025>) [3]. Laminin
IV  domain  is  also  found  in the perlecan protein, an integral component of
basement  membranes,  which  serves also as an attachment substrate for cells,
but it is not found in short laminin chains (alpha4 or beta3). The function of
this domain is not yet known.

The  domain  IV  of laminin beta chains displays no sequence homology to other
laminin  IV  domains,  we  thus  have  developed  two  profiles. The first one
recognized all laminin IV domains except the one found in laminin beta chains.
We have developed a second profile to recognize this atypical domain IV.

-Sequences known to belong to this class detected by the first profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Sequences known to belong to this class detected by the second profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: April 2005 / First entry.

[ 1] DOI=10.1002/(SICI)1097-0177(200006)218:2<213::AID-DVDY1>3.0.CO;2-R
     Colognato H., Yurchenco P.D.
     "Form and function: the laminin family of heterotrimers."
     Dev. Dyn. 218:213-234(2000).
     PubMed=10842354
[ 2] Yurchenco P.D., Wadsworth W.G.
     "Assembly and tissue functions of early embryonic laminins and
     netrins."
     Curr. Opin. Cell Biol. 16:572-579(2004).
     PubMed=15363809; DOI=10.1016/j.ceb.2004.07.013
[ 3] Sasaki M., Kleinman H.K., Huber H., Deutzmann R., Yamada Y.
     "Laminin, a multidomain protein. The A chain has a unique globular
     domain and homology with the basement membrane proteoglycan and the
     laminin B chains."
     J. Biol. Chem. 263:16536-16544(1988).
     PubMed=3182802

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