SSB (Sjögren Syndrome Antigen B)
Lupus La Protein, RNA-binding protein involved in RNA metabolism and autoimmunity
Gene Information Card
| Symbol | SSB |
|---|---|
| Full Name | Sjögren syndrome antigen B (autoantigen La) |
| Gene Type | protein-coding |
| Chromosomal Location | 2q31.1 |
| NCBI Gene ID | 6741 ncbi.nlm.nih.gov/gene/6741 |
| Ensembl ID | ENSG00000138385 |
| UniProt ID | P05455 |
| OMIM ID | 109090 |
| HGNC ID | 11316 |
| Aliases | La, La/SSB, LARP3, SS-B |
Description
The SSB gene encodes the La protein, a 47 kDa RNA-binding protein that protects nascent RNA polymerase III transcripts from exonucleolytic degradation and facilitates their maturation. La protein also participates in RNA metabolism, including tRNA processing, and is a major autoantigen in Sjögren syndrome and systemic lupus erythematosus. Autoantibodies against SSB are diagnostic markers for these autoimmune diseases.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Sjögren syndrome | Autoantibodies against SSB (La) target the La protein, contributing to glandular inflammation and dysfunction. | ClinVar, OMIM |
| Systemic lupus erythematosus (SLE) | Anti-SSB/La autoantibodies are present in a subset of SLE patients, associated with subacute cutaneous lupus and neonatal lupus. | ClinVar, OMIM |
| Neonatal lupus erythematosus | Maternal anti-SSB/La antibodies cross the placenta and cause fetal heart block and skin lesions. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Salivary gland | 12.5 | Medium |
| Lung | 8.3 | Medium |
| Spleen | 7.1 | Medium |
| Lymph node | 6.8 | Medium |
| Bone marrow | 5.9 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 15.2 | High expression |
| K562 | 10.1 | Medium expression |
| HepG2 | 9.4 | Medium expression |
| A549 | 8.7 | Medium expression |
| MCF7 | 7.3 | Medium expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | missense | <0.01% | Potential loss of function; not well characterized |
| c.124C>T (p.Arg42Cys) | missense | <0.01% | Unknown effect; rare variant |
| c.365G>A (p.Arg122Gln) | missense | <0.01% | Unknown effect; rare variant |
Mutation functional classification
Loss of Function (LOF)
No well-established loss-of-function mutations reported in SSB; homozygous knockout is likely lethal in humans.
Gain of Function (GOF)
No gain-of-function mutations described for SSB.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • RNA binding | • mRNA 3'-UTR binding |
| • tRNA binding | • nucleic acid binding |
| • cytoplasm | • nucleus |
| • nucleolus | • ribonucleoprotein complex |
Pathways
• RNA polymerase III transcription termination
• tRNA processing
• mRNA stabilization
Protein Summary
The La protein (UniProt P05455) is a 408-amino acid RNA-binding protein with a La motif and an RRM domain. It binds to the 3'-UUU-OH trailer of nascent RNA polymerase III transcripts, protecting them from exonucleases and facilitating folding and maturation. La also interacts with viral RNAs and is involved in translation regulation. Its autoantigenic properties make it a key biomarker in autoimmune diagnostics.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SSBP1 Knockout HEK293 Cell Line | EDJ-KQ5845 | Human | 6742 | Details Get a Quote |
| SSBP2 Knockout HEK293 Cell Line | EDJ-KQ8111 | Human | 23635 | Details Get a Quote |
| SSBP1 Knockout HCT 116 Cell Line | EDJ-KQ28044 | Human | 6742 | Details Get a Quote |
| SSBP2 Knockout A-549 Cell Line | EDJ-KQ33986 | Human | 23635 | Details Get a Quote |
| SSBP2 Knockout HeLa Cell Line | EDJ-KQ33988 | Human | 23635 | Details Get a Quote |
| SSBP1 Knockout A-549 Cell Line | EDJ-KQ29303 | Human | 6742 | Details Get a Quote |
| SSBP1 Knockout HeLa Cell Line | EDJ-KQ29305 | Human | 6742 | Details Get a Quote |
| SSBP2 Knockout HCT 116 Cell Line | EDJ-KQ32648 | Human | 23635 | Details Get a Quote |
| SSB Knockout HEK293 Cell Line | EDJ-KQ50660 | Human | 6741 | Details Get a Quote |
| SSBP3 Knockout HEK293 Cell Line | EDJ-KQ51125 | Human | 23648 | Details Get a Quote |
| SSB Knockout HeLa Cell Line | EDJ-KQ54568 | Human | 6741 | Details Get a Quote |
| SSBP3 Knockout HeLa Cell Line | EDJ-KQ55791 | Human | 23648 | Details Get a Quote |
| SSB Knockout A-549 Cell Line | EDJ-KQ63052 | Human | 6741 | Details Get a Quote |
| SSBP3 Knockout A-549 Cell Line | EDJ-KQ64287 | Human | 23648 | Details Get a Quote |
| SSB Knockout HCT 116 Cell Line | EDJ-KQ71526 | Human | 6741 | Details Get a Quote |
