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Cloning of cDNAs encoding human caldesmons
M B Humphrey1, H Herrera-Sosa, G Gonzalez
1Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030.
Gene
|March 15, 1992
Summary
Caldesmon (CDM) is an actomyosin regulatory protein. Human smooth muscle and non-muscle CDM cDNAs were cloned, revealing the non-muscle form arises from exon skipping.
Area of Science:
- Molecular Biology
- Cell Biology
Background:
- Caldesmon (CDM) is a regulatory protein involved in actomyosin function.
- CDM is characterized by distinct N-terminal and C-terminal binding domains and a central helical region.
Purpose of the Study:
- To clone and characterize human smooth muscle and non-muscle caldesmon (CDM) cDNAs.
- To investigate the structural differences and potential origins of different CDM isoforms.
Main Methods:
- Screening a human aorta cDNA library using an avian caldesmon (aCDM) cDNA probe.
- Cloning and sequencing of smooth muscle and non-muscle CDM cDNAs.
- Bioinformatic analysis of predicted protein structures and sequence identities.
Main Results:
- Human smooth muscle CDM (hCDM) cDNA is 3050-3630 nt long, with high identity (>90%) to aCDM in binding domains.
- Non-muscle hCDM is shorter, lacking the central helical domain, suggesting generation by exon skipping.
- Predicted smooth muscle protein is 793 aa; non-muscle form is predicted to be 537 aa if N-terminal domains are identical.
Conclusions:
- The non-muscle form of human caldesmon is generated through alternative splicing, specifically exon skipping of the central helical domain.
- Structural variations in caldesmon isoforms contribute to its diverse regulatory roles in different cell types.