The Eukaryotic Linear Motif resource for
Functional Sites in Proteins
Functional site class:
Paxillin LD motifs
Functional site description:
The paxillin LD motifs are recognized by proteins mainly involved in cytoskeleton reorganization at adhesion foci.
ELM Description:
The paxillin LD motif binds as an amphipathic helical peptide to the FAT domain in FAK and PYK2. Since these LD regions bind to other cytoskeletal/focal adhesion proteins, it is not clear to what extent the motif pattern is specified by the FAT domain interaction. It is possible that, if there are peptide motifs that only bind FAT domains, the motif conservation of the hydrophobic positions would be looser. However, the conserved negatively charged residue is clearly a FAT domain specificity determinant. Prolines are excluded from the helical positions that are otherwise unconserved and solvent exposed in the solved complexes.
Pattern: [LV][DE][^P][LM][LM][^P][^P]L[^P]
Pattern Probability: 0.0000069
Present in taxon: Eukaryota
Interaction Domain:
Focal_AT (PF03623) Focal adhesion targeting region (Stochiometry: 1 : 1)
PDB Structure: 3GM1
o See 4 Instances for LIG_FAT_LD_1
o Abstract
The paxillin LD motif was first found in the sequence of the protein paxillin and is named after a conserved Leu-Pro residue pair. Paxillin and its paralogues Leupaxin and TGFB1i1 are adaptor proteins that localize to the cytosolic side of focal adhesion complexes. Paxillin is a protein involved in integrin-mediated signalling for cell adhesion, motility and growth-factor inputs. It possesses five copies of the LD motif, short peptide sequences that bind as alpha-helices to the FAT domain of FAK and PYK2 kinases. Some of these repeat motifs also bind to FAT-like domains in Vinculin and GIT1 as well as to proteins with clearly different folds including the CH domain of alpha-parvin. Thus LD motifs appear to be part of complex multiway switching systems affecting cell state via the adhesion complexes. They can be targets for viral interference as has been reported for the BPV E6 protein.
The LD motif entry in ELM is based on the FAK and PYK2 FAT domain interactions. As more data accumulates, it may be desirable to define overlapping motifs for the other helical interactions made by the LD regions of the paxillin family proteins.
o 3 selected references:

o 9 GO-Terms:

o 4 Instances for LIG_FAT_LD_1
(click table headers for sorting; Notes column: =Number of Switches, =Number of Interactions)
Acc., Gene-, NameStartEndSubsequenceLogic#Ev.OrganismNotes
P49023 PXN
4 12 MDDLDALLADLESTTSHISK TP 15 Homo sapiens (Human)
P49023 PXN
266 274 SATRELDELMASLSDFKIQG TP 2 Homo sapiens (Human)
P49024 PXN
145 153 SNLSELDRLLLELNAVQHNP TP 1 Gallus gallus (Chicken)
O43294 TGFB1I1
158 166 SATLELDRLMASLSDFRVQN TP 2 Homo sapiens (Human)
Please cite: The Eukaryotic Linear Motif Resource ELM: 10 Years and Counting (PMID:24214962)

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