Photoactivatable biotinylation reagents are ideal when primary amines, sulfhydryls, carboxyls and carbohydrates are not available for labeling.

Photoactivatable biotinylation reagents can also be used to activate biotinylation at specific times in an experiment or during certain reaction conditions, by simply exposing the reaction to UV light at the specific time or condition.

The outside signal ( in this case, adrenaline ) binds to a receptor, which transmits a signal to the G protein, which transmits a signal to adenylate cyclase, which transmits a signal by converting adenosine triphosphate to cyclic adenosine monophosphate ( cAMP ).

Following activation of adenylate cyclase, the resulting cAMP acts as a second messenger by interacting with and regulating other proteins such as protein kinase A and cyclic nucleotide-gated ion channels.

Structure of adenylate cyclase

Among the target molecules of the active GTPase are adenylate cyclase and ion channels.

They always use the activation of adenylate cyclase as the next step in the signal chain.

The i stands for inhibition of the adenylate cyclase ; another effector molecule for this protein family is phospholipase C. Also, G < sub > t </ sub > and G < sub > g </ sub > proteins are summarized under this label due to sequence homologies.

An example is adenylate cyclase, which produces the second messenger cyclic AMP.

This is accomplished by direct stimulation of the membrane-associated enzyme adenylate cyclase.

While dopamine receptor D2 suppresses adenylate cyclase activity, the D1 receptor increases it.

The increased adenylate cyclase activity affects genetic expression in the nerve cell, a process which takes time.

They are coupled to G < sub > s </ sub > and increase the cellular concentrations of cAMP by the activation of the enzyme adenylate cyclase.

They are coupled to G < sub > i </ sub >/ G < sub > o </ sub > and decrease the cellular concentrations of cAMP by inhibition of adenylate cyclase.

These four receptor subtypes are further classified based on their ability to either stimulate or inhibit adenylate cyclase activity.

The A2A and A2B receptors couple to G < sub > s </ sub > and mediate the stimulation of adenylate cyclase, while the A1 and A3 adenosine receptors couple to G < sub > i </ sub > which inhibits adenylate cyclase activity.

Membrane fluidity affects function of enzymes such as adenylate cyclase and ion channels such as calcium, potassium, and sodium, which in turn affects receptor numbers and functioning, as well as serotonin neurotransmitter levels.

As secretin binds to these receptors, it stimulates adenylate cyclase activity and converts ATP to cyclic AMP.

All three are linked to G < sub > s </ sub > proteins ( although β < sub > 2 </ sub > also couples to G < sub > i </ sub >), which in turn are linked to adenylate cyclase.

These trigger 7TM receptors ( G protein-coupled receptors ), which activate adenylate cyclase.

These invaginations in the sarcoplasma contain a host of receptors ( prostacyclin, endothelin, serotonin, muscarinic receptors, adrenergic receptors ), second messenger generators ( adenylate cyclase, Phospholipase C ), G proteins ( RhoA, G alpha ), kinases ( rho kinase-ROCK, Protein kinase C, Protein Kinase A ), ion channels ( L type Calcium channels, ATP sensitive Potassium channels, Calcium sensitive Potassium channels ) in close proximity.

Nitric oxide and PGI2 stimulate soluble guanylate cyclase and membrane bound adenylate cyclase, respectively.

At first, it was thought that cannabinoid receptors mainly inhibited the enzyme adenylate cyclase ( and thereby the production of the second messenger molecule cyclic AMP ), and positively influenced inwardly rectifying potassium channels (= Kir or IRK ).

Recently discovered activities of adenylate cyclase toxin, including transmembrane pore formation and stimulation of calcium influx, may also contribute to the intoxication of phagocytes.

In neurons, calcium-sensitive adenylate cyclases are located next to calcium ion channels for faster reaction to Ca < sup > 2 +</ sup > influx ; they are suspected of playing an important role in learning processes.

This is supported by the fact that adenylate cyclases are coincidence detectors, meaning that they are activated only by several different signals occurring together.

In peripheral cells and tissues adenylate cyclases appear to form molecular complexes with specific receptors and other signaling proteins in an isoform-specific manner.

Luciferyl adenylate can additionally participate in a side reaction with O < sub > 2 </ sub > to form hydrogen peroxide and dehydroluciferyl-AMP.

The G-protein receptor can affect the function of adenylate cyclase or phospholipase C, an agonist of the receptor will upregulate the effects on the downstream pathway ( it will not necessarily upregulate the pathway itself ).

The α subunit is thought to be the effector region responsible for stimulation of adenylate cyclase ( involved the generation of cAMP ).

The D < sub > 4 </ sub > receptor is considered to be D < sub > 2 </ sub >- like in which the activated receptor inhibits the enzyme adenylate cyclase, thereby reducing the intracellular concentration of the second messenger cyclic AMP.

Epinephrine activates adenylate cyclase through a seven transmembrane receptor coupled to G < sub > s </ sub > which, in turn, activates adenylate cyclase to increase intracellular concentrations of cAMP.

Adenylate cyclase (, also known as adenylyl cyclase, adenyl cyclase or AC ) is an enzyme with key regulatory roles in nearly all cells.

It is synthesised from arginine and oxygen by the NO synthase and works through activation of soluble guanylyl cyclase, which when activated produces another second messenger, cGMP.

Upon ligand binding, the receptor undergoes conformation changes that stimulate the enzyme adenylyl cyclase, which leads to an increase in intracellular cAMP and subsequent activation of protein kinase A.

This is mediated via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell hyperpolarization by increasing outward K + flux.

Confirmation of the diagnosis is with tests that evaluate the degree of inhibition of adenylyl cyclase by ADP.

This, in turn, activates adenylyl cyclase, which synthesizes cAMP.

For example, the mRNA for GCC ( guanylyl cyclase c ), present only in the luminal aspect of intestinal epithelium, can be identified using molecular screening ( RT-PCR ) with an astonishing degree of sensitivity and exactitude.

Although membrane ion channels and protein phosphorylation are typically indirectly affected by G protein-coupled receptors via effector proteins ( such as phospholipase C and adenylyl cyclase ) and second messengers ( such as inositol triphosphate, diacylglycerol and cyclic AMP ), G proteins can short circuit the second-messenger pathway and gate the ion channels directly.

GABA < sub > B </ sub > receptors can also reduce the activity of adenylyl cyclase and decrease the cell ’ s conductance to Ca < sup > 2 +</ sup >.