Neurotransmitters : neuron to neuron signalling Hormones: secreted into the bloodstream to travel long distances Cytokines and Growth factors: activation of signalling cascades, growth factors are essential for the cell cycle

Intracellular receptors : nuclear receptors Extracellular receptors : Tyrosine kinase receptors and G-protein coupled receptors

Paracrine : made in one cell and have an effect on a local different cell Endocrine: secreted hormones travel through the blood stream to have an effect on distant cells Autocrine: signal acts on the same type of cell that secretes it

Metabotropic: affects metabolic events (G-protein coupled receptors) Catalytic: affects normal cellular processes via catalysis via proteins (tyrosine kinase linked receptors) Ionotropic : ligand gated ion channels

The addition of a highly charged phosphate group to a protein, which will affect the protein structure and consequently the function, turning the protein either on or off. Protein must have an amino acid with an OH group (serine, tyrosine, threonine)

Protein-OH -----> Protein-O-P (by protein kinase with the exchange of ATP to ADP) Protein O-P -----> Protein O-H (by protein phosphatase with the addition of water and loss of phosphate group)

Preproinsulin: initial form of insulin 110 amino acids Proinsulin: signal peptide is removed, covalent disulphide bonds are formed from cystine residues, 86 amino acids Insulin: protease further trims proinsulin to form 51 amino acid insulin, A and B chain held together by disulphide bonds.

PI3-kinase occurs at cell membrane