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Human Phosphatases
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Statistics

241 human active and 13 inactive phosphatases in total;
194 phosphatases have substrate data;
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336 protein substrates;
83 non-protein substrates;
1215 dephosphorylation interactions;
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299 KEGG pathways;
876 Reactome pathways;
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last scientific update:
11 Mar, 2019
last maintenance update:
01 Sep, 2023

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PKP4

Basic Information
Phosphatases
Pathway
Interacting Proteins
Phosphorylating Kinases

Gene Name	PKP4 (QuickGO)	Interactive visualization of PKP4 structures (A quick tutorial to explore the interctive visulaization) Representative structure: NA
Synonyms	PKP4
Protein Name	PKP4
Alternative Name(s)	Plakophilin-4;p0071;
Protein Family	Belongs to the beta-catenin family
EntrezGene ID	8502 (Comparitive Toxicogenomics)
UniProt AC (Human)	Q99569 (protein sequence)
Enzyme Class	N/A
Molecular Weight	131868 Dalton
Protein Length	1192 amino acids (AA)
Genome Browsers	NCBI \|
Crosslinking annotations	Query our ID-mapping table
Orthologues	Quest For Orthologues (QFO) \| GeneTree

Domain organization, Expression, Diseases

Localization, Function, Catalytic activity and Sequence

Motif information from Eukaryotic Linear Motif atlas (ELM)

Gene Ontology (P: Process; F: Function and C: Component terms)

KEGG Pathway
Reactome Pathway

Pathway ID	Pathway Name	Pathway Description (KEGG)
R-HSA-6805567	Keratinization.	Keratins are the major structural protein of vertebrate epidermis, constituting up to 85% of a fully differentiated keratinocyte (Fuchs 1995). Keratins belong to a superfamily of intermediate filament (IF) proteins that form alpha-helical coiled-coil dimers, which associate laterally and end-to-end to form approximately 10 nm diameter filaments. Keratin filaments are heteropolymeric, formed from equal amounts of acidic type I and basic /neutral type 2 keratins. Humans have 54 keratin genes (Schweitzer et al. 2006). They have highly specific expression patterns, related to the epithelial type and stage of differentiation. Roughly half of human keratins are specific to hair follicles (Langbein & Schweizer 2005). Keratin filaments bundle into tonofilaments that span the cytoplasm and bind to desmosomes and other cell membrane structures (Waschke 2008). This reflects their primary function, maintaining the mechanical stability of individual cells and epithelial tissues (Moll et al. 2008)
R-HSA-6809371	Formation of the cornified envelope.	As keratinocytes progress towards the upper epidermis, they undergo a unique process of cell death termed cornification (Eckhart et al. 2013). This involves the crosslinking of keratinocyte proteins such as loricrin and involucrin by transglutaminases and the breakdown of the nucleus and other organelles by intracellular and secreted proteases (Eckhart et al. 2000, Denecker et al. 2008). This process is strictly regulated by the Ca2+ concentration gradient in the epidermis (Esholtz et al. 2014). Loricrin and involucrin are encoded in ‘Epidermal Differentiation Complex’ linked to a large number of genes encoding nonredundant components of the CE (Kypriotou et al. 2012, Niehues et al. 2016). Keratinocytes produce specialized proteins and lipids which are used to construct the cornified envelope (CE), a heavily crosslinked submembranous layer that confers rigidity to the upper epidermis, allows keratin filaments to attach to any location in the cell membrane (Kirfel et al. 2003) and acts as a water-impermeable barrier. The CE has two functional parts: covalently cross-linked proteins (10 nm thick) that comprise the backbone of the envelope and covalently linked lipids (5 nm thick) that coat the exterior (Eckert et al. 2005). Desmosomal components are crosslinked to the CE to form corneodesmosomes, which bind cornified cells together (Ishida-Yamamoto et al. 2011). Mature terminally differentiated cornified cells consist mostly of keratin filaments covalently attached to the CE embedded in lipid lamellae (Kalinin et al. 2002). The exact composition of the cornified envelope varies between epithelia (Steinert et al. 1998); the relative amino-acid composition of the proteins used may determine differential mechanical properties (Kartasova et al. 1996)