Cell Crawling

Cell Crawling

The  process of cell crawling is first the leading edge extends via polymerisation of actin at its tip. then new adhesions are anchored by actin form on the under surface of the lamellipodium. The trailing edge (tail) of the cell detaches and is drawn forward by contraction of the cell body.

Lamellipida is a flattened extension of a cell, by which it moves over or adheres to a surface.

Within the lamellipodia are ribs of actin called microspikes, which, when they spread beyond the lamellipodium frontier, are called filopodia. The lamellipodium is born of actin nucleation in the plasma membrane of the cell and is the primary area of actin incorporation or microfilament formation of the cell.

The Lamellipidia form at the leading edge of the cell and growth of the lamellipodia driven by the growth of the branched actin. Focal adhesion points anchor cell to the surface and is released in the trailing edge of the cell and cytoplasm drawn forward by contraction.

Actin is a type of microfilament. G actin (gobular) monomers assemble into F actin (filamentous) polymers. A polymer has a polarity which means that is has a postive and minus end. F actin is made up og two strands coiled G actin and uses ATP to bind new G actin.

In the perfect world of a test tube, experimenters can do the polymerization process by adding salts to G- actin or can depolymerize F-actin by simply diluting the filaments. Cells, however, must maintain a nearly constant cytosolic ionic concentration and thus employ a different mechanism for controlling actin polymerization. The cellular regulatory mechanism involves several actin-binding proteins that either promote or inhibit actin polymerization. Here we discuss two such proteins that have been isolated and characterized.

**!!REMEMBER TO STAY POSITIVE LIKE A PROTON!!**