for National Geographic News. A massive new study of human genetic diversity reveals surprising insights into our species' evolution and migrationsâincluding support for the theory that the first modern humans originated in Africaâscientists said today.or National Geographic News. A massive new study of human genetic diversity reveals surprising insights into our species' evolution and migrationsâincluding support for the theory that the first modern humans originated in Africaâscientists said today.
Proteins are too large to move across the phospholipid bilayer of the cell membrane so therefore require help getting into (or out of) the cell. Proteins may be brought across the cell membrane by endocytosis - they may then be broken down into amino acid building blocks (by fusion of the endocytotic vesicles with the proteolytic enzyme containing lysosomes) which can then be used by the cell or moved out of the cell by transmembrane transport proteins.
Best Answer: Specific proteins embedded in the cell membrane can act as molecular signals that allow cells to communicate with each other. Protein receptors are found ubiquitously and function to receive signals from both the environment and other cells. These signals are transduced and passed in a different form into the cell. For example, a hormone binding to a receptor could open an ion channel in the receptor and allow calcium ions to flow into the cell. Other proteins on the surface of the cell membrane serve as markers that identify a cell to other cells. The interaction of these markers with their respective receptors forms the basis of cell-cell interaction in the immune system.