Conserved Site

Lysosome-associated membrane glycoprotein, conserved site (IPR018134)

Short name: LAMP_CS

Description

Lysosome-associated membrane glycoproteins (lamp) [PMID: 1939168] 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 (TM) followed by a very short cytoplasmic tail (C). In each of the duplicated domains, there are two conserved disulphide 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, which form major components of the lysosome membrane. In chicken lamp-1 is known as LEP100.

Also included in this entry is the macrophage protein CD68 (or macrosialin) [PMID: 8486654] 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.

Similar to CD68, mammalian lamp-3, which is expressed in lymphoid organs, dendritic cells and in lung, contains all the C-terminal regions but lacks the N-terminal lamp-like region [PMID: 9768752]. In a lamp-family protein from nematodes [PMID: 10862717] only the part C-terminal to the hinge is conserved.

There are two signatures in this entry, one is centred 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.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns
PROSITE patterns