Biology 201 B1 Assignment #2
A four question analysis on "The myosin-interacting protein SMYD1 is essential for sarcomere organization" by Just et al. (2011)
1.) Wild-type Fla Mutant (SMYD-deficient)
In the current study, the authors used a zebra fish mutant known as Flatline (fla). This mutant contains a nonsense mutation within the SMYD1 gene, consequently, these mutants show disturbed sarcomere assembly. The authors observed that fla mutants had properly assembled hearts with healthy myo- and endocardial cell layers but their cardiac tissue showed no contraction under stimulation. They also concluded that the cardiac electrical impulse was the same for both wild-type and …show more content…
Their key findings of defective myofibrillar organization was through assaying the muscle ultrastructure of fla mutants 48 hours post fertilization. The results are shown in Fig 1. above. These images show that sarcomerogenesis is absent in fast-twitch muscle tissues (Fig. 1D,F) and in cardiac tissue, but is very well defined in slow-twitch muscle tissue (Fig. 1H). Also, myosin bundles were never seen in fla mutant muscles, implying SMYD interferes with "early myosin assembly or stability" (Just et al., …show more content…
They are essential for the proper folding of thick filament myosin during myofibrillogenesis. Therefore, a decrease in these two specific molecular chaperones "results in the destabilization and degradation of their client protein myosin" (Barral et al., 1998; Hawkins et al., 2008; Landsverk et al., 2007).
When myosin cannot fold properly into its functional state, sarcomere formation is disrupted because of the importance that myosin has in maintaining organizational structure. A representational image of a sarcomere is shown above in Fig 4., and myosin 's importance is clearly seen as it forms the thick filaments that hold the sarcomeric unit together. This undeniable importance not only arises from the fact that myosin is the main molecular motor involved in muscle contraction, but also because of its structural formation from cross-linking in the M-line and its attachment to the Z-line through the elastic protein,
A four question analysis on "The myosin-interacting protein SMYD1 is essential for sarcomere organization" by Just et al. (2011)
1.) Wild-type Fla Mutant (SMYD-deficient)
In the current study, the authors used a zebra fish mutant known as Flatline (fla). This mutant contains a nonsense mutation within the SMYD1 gene, consequently, these mutants show disturbed sarcomere assembly. The authors observed that fla mutants had properly assembled hearts with healthy myo- and endocardial cell layers but their cardiac tissue showed no contraction under stimulation. They also concluded that the cardiac electrical impulse was the same for both wild-type and …show more content…
Their key findings of defective myofibrillar organization was through assaying the muscle ultrastructure of fla mutants 48 hours post fertilization. The results are shown in Fig 1. above. These images show that sarcomerogenesis is absent in fast-twitch muscle tissues (Fig. 1D,F) and in cardiac tissue, but is very well defined in slow-twitch muscle tissue (Fig. 1H). Also, myosin bundles were never seen in fla mutant muscles, implying SMYD interferes with "early myosin assembly or stability" (Just et al., …show more content…
They are essential for the proper folding of thick filament myosin during myofibrillogenesis. Therefore, a decrease in these two specific molecular chaperones "results in the destabilization and degradation of their client protein myosin" (Barral et al., 1998; Hawkins et al., 2008; Landsverk et al., 2007).
When myosin cannot fold properly into its functional state, sarcomere formation is disrupted because of the importance that myosin has in maintaining organizational structure. A representational image of a sarcomere is shown above in Fig 4., and myosin 's importance is clearly seen as it forms the thick filaments that hold the sarcomeric unit together. This undeniable importance not only arises from the fact that myosin is the main molecular motor involved in muscle contraction, but also because of its structural formation from cross-linking in the M-line and its attachment to the Z-line through the elastic protein,