unc-22 Antibody
Description
Definition and Target
The unc-22 antibody is a polyclonal antibody raised against a β-galactosidase fusion protein containing sequences from the unc-22 gene product of C. elegans . The unc-22 gene encodes twitchin, a giant intracellular muscle protein (~500–600 kDa) with kinase domains homologous to human titin . This antibody specifically labels the A-band region of C. elegans body wall muscles, pharyngeal muscles, and vulval muscles .
Key Properties
The antibody was validated using Tcl transposon insertion alleles and deficiency mutants, confirming its specificity to the unc-22 protein . In mutants like ct37 (deletion allele), the protein is undetectable, whereas st136::Tcl produces a truncated doublet .
Muscle Structure Analysis
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Localization: The antibody colocalizes with myosin heavy chain (unc-54) in the A-bands of wild-type muscles, as shown by immunofluorescence .
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Mutant Phenotypes: In unc-22 mutants, staining is reduced or absent, correlating with disorganized sarcomeres and impaired motility .
Functional Insights
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Twitchin regulates actin-myosin interactions via phosphorylation . The antibody helped identify that kinase-inactive mutants (e.g., unc-22(sf21)) exhibit hypercontraction, while null alleles (e.g., e66) cause severe sarcomere disarray .
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Dominant unc-22 alleles show conditional twitching under cholinergic agonists, reflecting stoichiometric requirements for twitchin .
Human Disease Relevance
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Twitchin homologs in humans (titin, OBSCN) are linked to cardiomyopathies and muscular dystrophies . The unc-22 antibody provides a model for studying these diseases .
Western Blot Data
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Wild-type extracts show a prominent ~500–600 kDa band, while unc-22 mutants (ct37) lack this band .
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Truncated proteins in st136::Tcl mutants migrate as a doublet .
Immunofluorescence Observations
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Wild-type staining overlaps with myosin in A-bands (Fig. 6 in ).
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In unc-54(st273) mutants (disorganized thick filaments), unc-22 protein distribution mirrors myosin disruption .
Technical Considerations
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Adsorption: Pre-adsorption with bacterial lysates eliminates non-specific reactivity .
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Mutant Controls: Essential for distinguishing background noise in immunoassays .
Comparative Insights
| Feature | Wild Type | unc-22 Mutants |
|---|---|---|
| Protein Size | 500–600 kDa | Absent/truncated |
| Sarcomere Organization | Normal | Disrupted |
| Motility | Normal | Twitching/paralysis |
Broader Implications
The unc-22 antibody has advanced understanding of:
Product Specs
Constituents: 50% Glycerol, 0.01M Phosphate Buffered Saline (PBS), pH 7.4
Target Background
UNC-22 (Twitchin) is a key regulator of muscle contraction and relaxation. It functions as a mechanosensor, unfolding in distinct steps in response to varying mechanical forces generated during muscle activity. Furthermore, it plays a crucial role in the structural organization of sarcomeres within body wall muscles.
Regulatory Mechanisms:
- Twitchin activation is mediated by MAK-1 kinase. Additional regulation may occur via the p38 MAP kinase pathway. PMID: 25851606
STRING: 6239.ZK617.1b.2
UniGene: Cel.23028
