We cloned and characterized two important human erythrocyte membrane skeletal proteins, namely protein 4.2 and E-tropomodulin. We discovered that protein 4.2 is a transglutaminase-like molecule without the cross-linking capability and proposed a hypothesis for protein 4.2 and transglutaminase to regulate the mechanical properties of erythrocyte membranes. We also identified two specific isoforms of tropomyosin (TM) in erythrocyte membranes and revealed that E-tropomodulin binds to the N-terminus of tropomyosin.
We further mapped the binding sites involved in the TM/E-tropomodulin interaction. The complex formed by TM5/5b and E-tropomodulin may function as a molecular ruler in determining the length of the actin protofilaments and thus the geometry of erythrocyte membrane skeleton.
More recently we created a E-tropomodulin-null mutation in mouse embryonic stem cells and mice. This allows us to investigate the role of E-tropomodulin in the mechanical properties of both erythroid and non-erythoid cells (e.g., cardiomyocytes and skeletal muscles) that express E-tropomodulin at a significant level. The knockout mice die embryonically with arrests in cardiac morphogenesis, yolk sac vasculogenesis, and embryo proper hematopoiesis.
- Creation of mouse models with targeted disruption of specific genes.
- Theory on the molecular ruler and geometry of erythrocyte membrane skeletons.
- Mapping protein binding sites with recombinant proteins.
- cDNA and genomic characterization of genes important for cell and membrane mechanics.
- Mechanical properties of genetically engineered cells and tissues.
- Molecular and mechanical defects in diseases (e.g., of heart, vessels, blood, and muscle).