PGGT1B Gene
Protein Geranylgeranyltransferase Type I Subunit Beta
Gene Information Card
| Symbol | PGGT1B |
|---|---|
| Full Name | Protein Geranylgeranyltransferase Type I Subunit Beta |
| Gene Type | protein-coding |
| Chromosomal Location | 5q11.2 |
| NCBI Gene ID | 5229 ncbi.nlm.nih.gov/gene/5229 |
| Ensembl ID | ENSG00000164211 |
| UniProt ID | P53609 |
| OMIM ID | 602032 |
| HGNC ID | 8896 |
| Aliases | GGTase-I, GGTI, RABGGTB, beta GGTase I |
Description
PGGT1B encodes the beta subunit of protein geranylgeranyltransferase type I (GGTase-I), an enzyme that catalyzes the addition of a geranylgeranyl isoprenoid group to cysteine residues in proteins containing a C-terminal CAAX motif. This prenylation is essential for membrane localization and function of small GTPases such as Rho, Rac, and Cdc42. The enzyme is a heterodimer composed of alpha and beta subunits; the beta subunit confers substrate specificity.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Choroideremia | Deficiency in geranylgeranylation of Rab proteins leads to retinal degeneration; PGGT1B mutations may contribute indirectly via altered prenylation of Rab escort proteins. | Limited evidence; primarily associated with CHM (REP1) gene. |
| Cancer (various) | Overexpression of GGTase-I promotes Rho GTPase prenylation and oncogenic signaling; PGGT1B upregulation observed in breast, lung, and pancreatic cancers. | COSMIC; literature review |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Testis | 12.5 | Medium |
| Adrenal gland | 10.2 | Medium |
| Thyroid | 9.8 | Medium |
| Brain | 7.3 | Low |
| Liver | 6.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 15.0 | High expression |
| HeLa | 12.3 | Medium expression |
| A549 | 11.5 | Medium expression |
| MCF7 | 9.2 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1015C>T (p.Arg339Trp) | Missense | <0.01% | Unknown functional effect |
| c.1246G>A (p.Gly416Ser) | Missense | <0.01% | Unknown functional effect |
Mutation functional classification
Loss of Function (LOF)
No confirmed loss-of-function mutations reported in ClinVar or COSMIC.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations described.
View complete mutation data：
Gene Ontology (GO)
| • Rab geranylgeranyltransferase activity (GO:0004663) | • protein geranylgeranyltransferase complex (GO:0005961) |
| • protein geranylgeranylation (GO:0018344) | • small GTPase mediated signal transduction (GO:0007264) |
Pathways
• Protein prenylation (Reactome: R-HSA-597592)
• Rho GTPase cycle (Reactome: R-HSA-194315)
Protein Summary
The beta subunit of geranylgeranyltransferase type I (GGTase-I) is a 377-amino acid protein that forms a heterodimer with the alpha subunit (FNTA). It recognizes CAAX motifs at the C-terminus of target proteins and catalyzes the transfer of a geranylgeranyl group from geranylgeranyl pyrophosphate. This modification is critical for the membrane association and biological activity of Rho family GTPases. The protein is ubiquitously expressed with highest levels in testis and adrenal gland.
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