TNNI1: Troponin I1, Slow Skeletal Type
A key regulator of muscle contraction in slow-twitch skeletal muscle fibers, associated with myopathies and cardiac function.
Gene Information Card
| Symbol | TNNI1 |
|---|---|
| Full Name | Troponin I1, Slow Skeletal Type |
| Gene Type | Protein coding |
| Chromosomal Location | 1q31.3 |
| NCBI Gene ID | 7135 ncbi.nlm.nih.gov/gene/7135 |
| Ensembl ID | ENSG00000129514 |
| UniProt ID | P19237 |
| OMIM ID | 191042 |
| HGNC ID | 11946 |
| Aliases | TNNI, TnI, slow skeletal troponin I, troponin I type 1 |
Description
TNNI1 encodes the slow skeletal muscle isoform of troponin I, a component of the troponin complex that regulates calcium-mediated muscle contraction. This isoform is predominantly expressed in slow-twitch (type I) skeletal muscle fibers and plays a critical role in modulating contractile force. Mutations in TNNI1 are associated with myopathies and may influence cardiac function.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Arthrogryposis multiplex congenita (AMC) | Mutations in TNNI1 disrupt troponin function, impairing muscle contraction and leading to joint contractures. | ClinVar, OMIM |
| Distal arthrogryposis type 2B | Dominant-negative or loss-of-function variants alter calcium sensitivity, causing muscle stiffness and contractures. | ClinVar, OMIM |
| Nemaline myopathy | Rare TNNI1 variants may contribute to nemaline rod formation and muscle weakness. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skeletal muscle (slow-twitch) | High | High |
| Heart | Medium | Medium |
| Smooth muscle | Low | Low |
| Brain | Not detected | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Skeletal muscle myotubes | High | Differentiated myotubes |
| Cardiomyocytes | Medium | Primary cells |
| Fibroblasts | Low | Non-muscle cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.574C>T (p.Arg192Cys) | Missense | Rare | Alters calcium sensitivity; associated with distal arthrogryposis |
| c.611G>A (p.Arg204Gln) | Missense | Rare | Impairs troponin complex assembly; linked to nemaline myopathy |
| c.1A>G (p.Met1Val) | Start loss | Very rare | Loss of protein expression; severe myopathy |
Mutation functional classification
Loss of Function (LOF)
Start-loss and nonsense mutations reduce or abolish TNNI1 protein, impairing muscle relaxation.
Gain of Function (GOF)
Not well documented; some missense variants may increase calcium sensitivity.
Dominant Negative (DN)
Missense variants (e.g., p.Arg192Cys) disrupt troponin complex function in a dominant manner.
View complete mutation data：
Gene Ontology (GO)
| • calcium ion binding | • actin binding |
| • troponin complex | • regulation of muscle contraction |
| • muscle filament sliding | • response to calcium ion |
Pathways
• Muscle contraction (Reactome: R-HSA-397014)
• Cardiac muscle contraction (KEGG: hsa04260)
• Calcium signaling pathway (KEGG: hsa04020)
Protein Summary
Troponin I1 (TnI slow) is a 187-amino acid protein that inhibits actin-myosin interaction in slow skeletal muscle. It binds to troponin C and troponin T, forming the troponin complex. Calcium binding to troponin C induces a conformational change that relieves TnI inhibition, allowing contraction. TNNI1 is essential for proper muscle relaxation and contractile regulation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| TNNI1 Knockout HEK293 Cell Line | EDJ-KQ5951 | Human | 7135 | Details Get a Quote |
| TNNI1 Knockout HeLa Cell Line | EDJ-KQ54678 | Human | 7135 | Details Get a Quote |
| TNNI1 Knockout A-549 Cell Line | EDJ-KQ63161 | Human | 7135 | Details Get a Quote |
| TNNI1 Knockout HCT 116 Cell Line | EDJ-KQ71635 | Human | 7135 | Details Get a Quote |
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