Seroatlas · Human Serome Atlas

PPP1R21

Protein phosphatase 1 regulatory subunit 21

Also known as: CCDC128, FLJ16566, KLRAQ1, PPR21_HUMAN

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession: Q6ZMI0
Gene: PPP1R21
Ensembl: ENSG00000162869
Chromosome: 2
Canonical length: 780 aa
Protein class: Disease related genes, Human disease related genes, Predicted intracellular proteins
Subcellular location: Nucleoplasm,Vesicles

OverviewNCBI Gene

Enables RNA binding activity. Located in early endosome. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

780 residues, UniProt reviewed canonical sequence.

>Q6ZMI0|PPP1R21
     1  MASAELQGKY QKLAQEYSKL RAQNQVLKKG VVDEQANSAA LKEQLKMKDQ SLRKLQQEMD
    61  SLTFRNLQLA KRVELLQDEL ALSEPRGKKN KKSGESSSQL SQEQKSVFDE DLQKKIEENE
   121  RLHIQFFEAD EQHKHVEAEL RSRLATLETE AAQHQAVVDG LTRKYMETIE KLQNDKAKLE
   181  VKSQTLEKEA KECRLRTEEC QLQLKTLHED LSGRLEESLS IINEKVPFND TKYSQYNALN
   241  VPLHNRRHQL KMRDIAGQAL AFVQDLVTAL LNFHTYTEQR IQIFPVDSAI DTISPLNQKF
   301  SQYLHENASY VRPLEEGMLH LFESITEDTV TVLETTVKLK TFSEHLTSYI CFLRKILPYQ
   361  LKSLEEECES SLCTSALRAR NLELSQDMKK MTAVFEKLQT YIALLALPST EPDGLLRTNY
   421  SSVLTNVGAA LHGFHDVMKD ISKHYSQKAA IEHELPTATQ KLITTNDCIL SSVVALTNGA
   481  GKIASFFSNN LDYFIASLSY GPKAASGFIS PLSAECMLQY KKKAAAYMKS LRKPLLESVP
   541  YEEALANRRI LLSSTESREG LAQQVQQSLE KISKLEQEKE HWMLEAQLAK IKLEKENQRI
   601  ADKLKNTGSA QLVGLAQENA AVSNTAGQDE ATAKAVLEPI QSTSLIGTLT RTSDSEVPDV
   661  ESREDLIKNH YMARIVELTS QLQLADSKSV HFYAECRALS KRLALAEKSK EALTEEMKLA
   721  SQNISRLQDE LTTTKRSYED QLSMMSDHLC SMNETLSKQR EEIDTLKMSS KGNSKKNKSR

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against PPP1R21 can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability: Intracellular
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.42
Highest tissue expression: 32 nTPM

Expression across tissuesHPA

Tissue

parathyroid gland: 32 nTPM
kidney: 26 nTPM
thyroid gland: 20 nTPM
epididymis: 19 nTPM
cerebral cortex: 16 nTPM
fallopian tube: 14 nTPM

Single-cell type

proximal tubule cells: 358 nCPM
neutrophils: 301 nCPM
oligodendrocytes: 289 nCPM
neutrophil progenitors: 226 nCPM
sertoli cells: 206 nCPM
hofbauer cells: 186 nCPM

Immune cell

basophil: 19 nTPM
neutrophil: 12 nTPM
eosinophil: 8.2 nTPM
naive B-cell: 6.8 nTPM
naive CD4 T-cell: 6.5 nTPM
naive CD8 T-cell: 5.5 nTPM

Brain region

white matter: 43 nTPM
basal ganglia: 32 nTPM
cerebral cortex: 30 nTPM
thalamus: 28 nTPM
midbrain: 28 nTPM
medulla oblongata: 28 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about PPP1R21.

Disease | AllUniProt

Conditions PPP1R21 is implicated in, by any mechanism.

Neurodevelopmental disorder with hypotonia, facial dysmorphism, and brain abnormalities (NEDHFBA) MIM:619383

Disease | GeneticClinVar

21 pathogenic / likely-pathogenic of 244 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Neurodevelopmental disorder with hypotonia, facial dysmorphism, and brain abnormalities
Neurodevelopmental disorder with hypotonia
Inborn genetic diseases
Thyroid cancer, nonmedullary, 1

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance): 0.69
gnomAD pLI: 0
gnomAD missense Z: -1.92
DepMap mean gene effect: -0.07
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 7% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

regulation of intracellular mRNA localization

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

Protein phosphatase 1 regulatory subunit 21, N-terminal
Protein phosphatase 1 regulatory subunit 21, six-helix bundle
Protein phosphatase 1 regulatory subunit 21
Protein phosphatase 1 regulatory subunit 21, C-terminal
Predicted coiled-coil domain-containing protein
Protein phosphatase 1 regulatory subunit 21, six-helix bundle
Protein phosphatase 1 regulatory subunit 21, C-terminal

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of PPP1R21 in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads PPP1R21 as an antibody target. Whether an autoantibody or antibody against PPP1R21 could matter depends on whether native PPP1R21 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

PPP1R21 is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label PPP1R21 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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