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* Lysosome-associated membrane glycoproteins signatures *
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Lysosome-associated membrane  glycoproteins (lamp) [1] are  integral  membrane
proteins, specific to lysosomes,  and whose exact biological  function  is not
yet clear.   Structurally,  the  lamp proteins   consist  of   two  internally
homologous  lysosome-luminal domains separated by a proline-rich hinge region;
at the C-terminal extremity there is a transmembrane region followed by a very
short cytoplasmic tail.   In each  of  the  duplicated domains, there  are two
conserved disulfide bonds. This structure is schematically  represented in the
figure below.

   +-----+            +-----+         +-----+            +-----+
   |     |            |     |         |     |            |     |
  xCxxxxxCxxxxxxxxxxxxCxxxxxCxxxxxxxxxCxxxxxCxxxxxxxxxxxxCxxxxxCxxxxxxxx
  <--------------------------><Hinge><--------------------------><TM><C>

In mammals, there are two closely related types of lamp: lamp-1 and lamp-2. In
chicken lamp-1 is known as LEP100.

The macrophage protein  CD68 (or macrosialin) [2] is  a  heavily  glycosylated
integral membrane  protein whose structure  consists  of  a  mucin-like domain
followed by a proline-rich hinge; a  single lamp-like domain;  a transmembrane
region and a short cytoplasmic tail.

We developed two signature patterns for this family of proteins. The first one
is centered  on the  first  conserved  cysteine of the duplicated domains. The
second corresponds  to  a  region  that  includes  the extremity of the second
domain, the totality of the transmembrane region and the cytoplasmic tail.

-Consensus pattern: [STA]-C-[LIVM]-[LIVMFYW]-A-x-[LIVMFYW]-x(3)-[LIVMFYW]-
                    x(3)-Y
                    [C is involved in a disulfide bond]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for CD68s.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Note: the pattern will fail to detect the second copy of the domain in lamp-2
 and the first copy of chicken LEP100.

-Consensus pattern: C-x(2)-D-x(3,4)-[LIVM](2)-P-[LIVM]-x-[LIVM]-G-x(2)-[LIVM]-
                    x-G-[LIVM](2)-x-[LIVM](4)-A-[FY]-x-[LIVM]-x(2)-[KR]-[RH]-
                    x(1,2)-[STAG](2)-Y-[EQ]
                    [C is involved in a disulfide bond]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Last update: June 1994 / Patterns and text revised.

[ 1] Fukuda M.
     J. Biol. Chem. 266:21327-21330(1991).
[ 2] Holness C.L., da Silva R.P., Fawcett J., Gordon S., Simmons D.L.
     J. Biol. Chem. 268:9661-9666(1993).