Primary-The amino acid sequence
Secondary-The alpha helices and beta sheets
Tertiary-Amino acid to amino acid interactions (disulfide bonds, etc.)
Enzymes-Alter a substrate that binds to its active site. Mainly works in hydrolysis and dehadration synthesis. Names most likely end with -ase e.g. lactase, phosphofructokinase
Messangers-Are sent or recieved and cause a reaction. For example nuerotransmitters in the nervous system bind to ligand gated ion channels, hormones.
Receptors-Recieve a message and signal a reaction. E.g. tyrosine-kinase receptors, ligand gated ion channels
Transport-Active and passive transport. K+/Na+ pump, voltage-gated ion channels in nervous system.
Motion-Bind to structures like actin and move. E.g. myosin heads of muscle cells.
Structure-Support cell structure and used as pathways for motion proteins. E.g. actin and myosin.
Proteins are most commonly activated by ATP (adenosine triphosohate) which causes a conformational change in the protein.
Source: Campbell Biology Seventh Edition AP Edition
Three dimensional structure of a protein influences directly the protein function.
All essential functions inside biological processes are provided by proteins. Proteins are involved in transmitting nerve impulses and in control of growth and differentiation.
For instance, collagen is a connective tissue protein found in bone, skin cartilage, tendons, etc. Disintegration of this protein leads to scurvy.
In rheumatic arthritis collagen is found disrupted
Other examples of proteins involved in biological processes are: Oxytocin and Vasopressin that stimulate lactation.