I. Physical Principles of Organization in Biological Membranes



Biological membranes make up the boundaries of cells and other internal organelles such as mitochondria, Golgi complex, endosomes, etc. They act as selective barriers to different molecules and are responsible for the survival of a cell. Understanding the organization and behavior of biological membranes is important in many biological processes including cell motility, endo- and exo-cytosis, cell-cell signaling, and immunological synapses. Biological membranes, according to the well-known Singer and Nicholson’s fluid mosaic model, are considered to be a two dimensional liquid where proteins and lipids diffuse freely with no organization. However, evidences contrary to this model are mounting where single molecule spectroscopic techniques show that biological membranes possess some level of organization, although the general underlying principles are unknown. I am interested in uncovering these principles of organization.

The physical state of the biological membranes at any instant of time may depend on many complex chemical, thermal, mechanical and interrelated changes in the surroundings. However, I concentrate on the behavior that results from changes in surface tension (pressure) and temperature. I am primarily interested in understanding the fundamental physical forces of interaction between different intra-membrane constituents, which may dynamically change the state of the biological membranes at different length and time scales. 

I am primarily motivated by the following biological processes: (i) Vacoule or synaptic fusion (ii) Immunological synapses (ii) Endocytosis and exocytosis and (iv) Eukaryotic motility.

The fundamental questions I am interested in addressing are: 

  • What are the fundamental physical forces involved in the lateral organization of proteins and lipids in membranes?
  • How do actin networks affect the lateral organization of biological membranes?
  • How do the lateral organization of proteins drive membrane shape changes at the macroscopic level? 
  • How do we explain the genesis of organelles? How do biological membranes exist in different shapes? 


 

© Kranthi K. Mandadapu