Presentation on theme: "Intracellular Compartments and Protein Sorting Haixu Tang School of Informatics."— Presentation transcript:
Intracellular Compartments and Protein Sorting Haixu Tang School of Informatics
The major intracellular compartments of an animal cell
Relative Volumes Occupied by the Major Intracellular Compartments INTRACELLULAR COMPARTMENTPERCENTAGE OF TOTAL CELL VOLUME Cytosol54 Mitochondria22 Rough ER cisternae9 Smooth ER cisternae plus Golgi cisternae 6 Nucleus6 Peroxisomes1 Lysosomes1 Endosomes1
Hypothetical schemes for the evolutionary origins of some organelles
Four distinct families 1)the nucleus and the cytosol, which communicate through nuclear pore complexes and are thus topologically continuous (although functionally distinct); 2)all organelles that function in the secretory and endocytic pathways, including the ER, Golgi apparatus, endosomes, lysosomes, the numerous classes of transport intermediates such as transport vesicles, and possibly peroxisomes; 3) the mitochondria; 4)the plastids (in plants only).
Construction of Membrane-enclosed Organelles Require Information in the Organelle Itself The information required to construct a membrane- enclosed organelle does not reside exclusively in the DNA that specifies the organelle's proteins. Epigenetic information in the form of at least one distinct protein that preexists in the organelle membrane is also required, and this information is passed from parent cell to progeny cell in the form of the organelle itself. Presumably, such information is essential for the propagation of the cell's compartmental organization, just as the information in DNA is essential for the propagation of the cell's nucleotide and amino acid sequences.
Nuclear lamina Consists of "intermediate filaments", 30-100 nm thick. These intermediate filaments are polymers of lamin, ranging from 60-75 kD. A-type lamins are inside, next to nucleoplasm; B-type lamins are near the nuclear membrane (inner). They may bind to integral proteins inside that membrane. The lamins may be involved in the functional organization of the nucleus.