MAGUK p55 subfamily member 7 (MPP7)

The protein contains 576 amino acids for an estimated molecular weight of 65524 Da.

 

Acts as an important adapter that promotes epithelial cell polarity and tight junction formation via its interaction with DLG1. Involved in the assembly of protein complexes at sites of cell-cell contact. (updated: Jan. 7, 2015)

Protein identification was indicated in the following studies:

  1. Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
  2. Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
  3. Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
  4. Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
  5. D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
  6. Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.

Methods

The following articles were analysed to gather the proteome content of erythrocytes.

The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.

PublicationIdentification 1Uniprot mapping 2Not mapped /
Obsolete
TrEMBLSwiss-Prot
Goodman (2013)2289 (gene list)227853205992269
Lange (2014)123412347281224
Hegedus (2015)2638262202352387
Wilson (2016)165815281702911068
d'Alessandro (2017)18261817201815
Bryk (2017)20902060101081942
Chu (2018)18531804553621387

1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry

The compilation of older studies can be retrieved from the Red Blood Cell Collection database.

The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.

No sequence conservation computed yet.

This protein is annotated as membranous in UniProt.


Interpro domains
Total structural coverage: 44%
Model score: 59

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VariantDescription
dbSNP:rs2997211

No binding partner found

The reference OMIM entry for this protein is 610973

Membrane protein, palmitoylated 7; mpp7

DESCRIPTION

Membrane-associated guanylate kinases (MAGUKs) are important adaptor proteins involved in the assembly of protein complexes at sites of cell-cell contact. They are found in synapses, adherens junctions, and tight junctions. All MAGUKs contain at least 1 PDZ domain, an SH3 domain, and a GUK domain, and many contain 1 or 2 L27 domains, which are involved in multimerization of MAGUKs. MPP7 belongs to the p55 stardust subfamily of MAGUKs, which is named for a Drosophila gene required for establishment of cell polarity in the developing fly embryo (Bohl et al., 2007).

CLONING

By searching databases for homologs of MPP5 (606958), Katoh and Katoh (2004) identified MPP7. The deduced 576-amino acid protein has 2 L27 domains (L27N and L27C) at its N terminus, followed by a PDZ domain, an SH3 domain, and a C-terminal GUK domain. It shares 93% amino acid identity with mouse Mpp7, 76% identity with the zebrafish humpback protein, and 56% identity with human MPP3 (601114). In silico expression analysis suggested that MPP7 is widely expressed.

GENE FUNCTION

Bohl et al. (2007) found that MPP7 formed a tripartite complex with DLG1 (601014) and LIN7A (603380) or LIN7C in vitro and in vivo. MPP7 dimerized with the LIN7 proteins through its L27C domain. The LIN7/MPP7 dimer then linked to DLG1 though the L27N domain of MPP7. This complex localized to epithelial adherens junctions in transfected Madin-Darby canine kidney cells. Expression of an MPP7 construct lacking either the PDZ or SH3 domain redistributed MPP7, DLG1, and LIN7 into the soluble cytoplasmic fraction. Stucke et al. (2007) showed that the L27N domain of endogenous MPP7 bound DLG1 in human epithelial cells. The SH3-HOOK domain of MPP7 interacted with MPP5, and in turn MPP5 interacted with CRB3 (609737). MPP7 and DLG1 colocalized at the lateral surface of epithelial cells, and they overlapped with markers of adherens junctions and tight junctions. Recruitment of MPP7 to the plasma membrane was dependent on its L27N-mediated interaction with DLG1 and on CRB3-dependent recruitment via the SH3-HOOK domain of MPP7. Loss of either DLG1 or MPP7 from epithelial cells resulted in a significant defect in assembly and maintenance of functional tight junctions. Stucke et al. (2007) concluded that formation of the DLG1-MPP7 complex promotes epithelial cell polarity and tight junction formation.

GENE STRUCTURE

Katoh and Katoh (2004) determined that the MPP7 gene contains at least 19 exons.

MAPPING

By genomic sequence analysis, Katoh and Katoh (2004) mapped the MPP7 gene to chromosome 10p12.1. ... More on the omim web site

Subscribe to this protein entry history

Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated

Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated

Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated

March 25, 2017: Additional information
No protein expression data in P. Mayeux work for MPP7

March 16, 2016: Protein entry updated
Automatic update: OMIM entry 610973 was added.

Feb. 24, 2016: Protein entry updated
Automatic update: model status changed