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508 || AWSAR Awarded Popular Science Stories - 2019
other important ions to enter the boundary through appropriate gates (ion channels). The membrane proteins, helping in maintaining the integrity of the cell, act as our Border Security Force. The selective nature of the membrane proteins in letting the molecules is termed as selective permeability of the membranes and is an essential part of our defense system.
Like any happy story, a happy home would be invaded by villains known by several names such as viruses, pathogens, infectious microbes, and pollutants.
The imperialist viruses exploit their own sticky fluidic membranes to fuse with one of ours’, gaining access to enter into our boundary. On entering, viruses take control of our entire cell machinery to manufacture their essential products such as nucleic acids and proteins similar to colonialism. When the security is breached and our defense is compromised, any other sidekicks of the main villain can enter and infuse
further damage to the happy
home (cells). In a similar way,
pollutants such as heavy metal
ions from contaminated water
and air gain access into our
cell boundary through the ion
channel gates by mimicking
calcium and sodium ions,
deceiving the membrane. Once
they breach the boundary, they
destabilize that home, leading
to the catastrophic destruction
of the entire neighborhood.
My work focuses on what really happens inside the cells after the attack by heavy metals such as lead and mercury. We are working on a small protein molecule called “scramblase,” anchored to this fluidic membrane. Scramblase, a membrane protein, plays the lead role in our story. Scramblases help in identifying and clearing the infected cells by initiating the response to several incoming attacks.
Scramblases are a family of four homologous proteins located in the membrane of our cells. Unlike other membrane proteins, these are relatively smaller in size with a prominent function. Among the scramblases, the third member is my major protein of interest. The third little brother of scramblase brothers resides within the mitochondrial membrane. Mitochondria are the powerhouse of the cell providing energy to the cell. The powerhouse within our cell is highly disturbed by the entry of heavy metal pollutants. Mitochondria are the first responders within the home for an incoming attack by the metal ions. They undergo a series of changes and trigger our internal armed forces (effector caspases) to shut the infected cell and program its death by a process called apoptosis.
Scramblases are calcium-dependent proteins that get activated when the intracellular calcium levels increase by 1000-folds under
abnormal circumstances. Under normal conditions, the calcium levels within cells are minimal and the scramblase activity is lower. The increased amount of calcium binds with the calcium-binding region of the scramblase and activates the membrane protein. Activated scramblases flip the charged lipids hidden in the inner layer of the membrane to the outer layer. The exposure
of charged lipids raises the alarm and is termed as the “hallmark of apoptosis.” The exposed phospholipids act as the key signal in identifying the infected cells termed as apoptotic cells. The boundary wall of the cells with the red flag raised is the signal for scavengers (phagocytic cells) called natural killer cells and macrophages. Macrophages and natural killer cells engulf the apoptotic cells resulting in their clearance, preventing
   Like any happy story, a happy home would be invaded by villains known by several names such as viruses, pathogens, infectious microbes, and pollutants.
  











































































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