This primase is structurally similar to many viral RNA dependent RNA polymerases, reverse transcriptases, cyclic nucleotide generating cyclases and DNA polymerases of the A / B / Y families that are involved in DNA replication and repair.

* HCN channel, a type of hyperpolarization-activated cyclic nucleotide gated channels

A cyclic nucleotide is any nucleotide in which the phosphate group is bonded to two of the sugar's hydroxyl groups, forming a cyclical or ring structure.

Usually, people speaking of phosphodiesterase are referring to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below.

The cyclic nucleotide phosphodiesterases comprise a group of enzymes that degrade the phosphodiester bond in the second messenger molecules cAMP and cGMP.

They regulate the localization, duration, and amplitude of cyclic nucleotide signaling within subcellular domains.

Because RETGC-1 produces cGMP which keeps cyclic gated nucleotide channels open allowing the influx of calcium, this mutation causes extremely high intracellular calcium levels.

The next steps involve extension-based sequencing with cyclic washes of the flow cell with fluorescently labeled nucleotides ( one nucleotide type at a time, as with the Sanger method ).

There is a cyclic nucleotide binding domain ( CNBD ) and connection region to the S6 segment in the carboxy terminal.

When a ligand binds to the β-pleated sheet, this bound cyclic nucleotide stabilizes the movement of the α-helix toward the β-pleated sheet in each subunit, pulling the α-helices away from each other.

Other sequence differences are seen in plant CNG channels, particularly in the cyclic nucleotide binding domain ( CNBD ).

They convert light signals to nerve impulses via cyclic nucleotide gated ion channels, which work by increasing the charge differential across the cell membrane ( i. e. hyperpolarization.

* Weiss, B .: Differential activation and inhibition of the multiple forms of cyclic nucleotide phosphodiesterase.

* Fertel, R. and Weiss, B .: Properties and drug responsiveness of cyclic nucleotide phosphodiesterases of rat lung.

: Selective cyclic nucleotide phosphodiesterase inhibitors as potential therapeutic agents.

Reduced levels of cytosolic cGMP cause cyclic nucleotide gated channels to close preventing further influx of Na + and Ca2 +.

The phosphodiesterase ( PDE ) isozymes, found in several tissues including the rod and cone photoreceptor cells of the retina, belong to a large family of cyclic nucleotide PDEs that catalyze cAMP and cGMP hydrolysis.

Other enzymes that may be present in the genome include papain-like proteases, ADP-ribose / poly ( ADP-ribose )- binding and / or ADP-ribose 1 "- phosphatase activities and cyclic nucleotide phosphodiesterase.

It has been shown in studies that transport of HCN ( hyperpolarization activated cyclic nucleotide ) gated channel isoforms to dendritic fields of CA1 pyramidal neurons in the hippocampus occurs in an age-specific manner in the developing hippocampus.

If the order of a group G is relatively small and the subgroup H is known to be uncomplicated ( for example, a cyclic group ), then the algorithm can be carried out by hand and gives a reasonable description of the group G. Using their algorithm, Coxeter and Todd showed that certain systems of relations between generators of known groups are complete, i. e. constitute systems of defining relations.

# The cyclic group, or

The two primary isomers of carotene, α-carotene and β-carotene, differ in the position of a double bond ( and thus a hydrogen ) in the cyclic group at one end ( left in the diagram here ).

* A cyclic group with prime order ;

Infinite cyclic fundamental group.

Rader's algorithm, exploiting the existence of a generator for the multiplicative group modulo prime, expresses a DFT of prime size as a cyclic convolution of ( composite ) size, which can then be computed by a pair of ordinary FFTs via the convolution theorem ( although Winograd uses other convolution methods ).

For example, the cyclic group of addition modulo n can be obtained from the integers by identifying elements that differ by a multiple of n and defining a group structure that operates on each such class ( known as a congruence class ) as a single entity.

Similarly, the multiplicative group of the field is a cyclic group.

A monosaccharide often switches from the acyclic ( open-chain ) form to a cyclic form, through a nucleophilic addition reaction between the carbonyl group and one of the hydroxyls of the same molecule.

In terms of groups, the residue class is the coset of a in the quotient group, a cyclic group.

* Locally cyclic group

: An N-terminal glutamine can attack itself, forming a cyclic pyroglutamate group.

Equivalently, a module M is simple if and only if every cyclic submodule generated by a non-zero element of M equals M. Simple modules form building blocks for the modules of finite length, and they are analogous to the simple groups in group theory.

A consequence of the theorem is that the order of any element a of a finite group ( i. e. the smallest positive integer number k with a < sup > k </ sup > = e, where e is the identity element of the group ) divides the order of that group, since the order of a is equal to the order of the cyclic subgroup generated by a.

The theorem also shows that any group of prime order is cyclic and simple.

For general groups, Cauchy's theorem guarantees the existence of an element, and hence of a cyclic subgroup, of order any prime dividing the group order ; Sylow's theorem extends this to the existence of a subgroup of order equal to the maximal power of any prime dividing the group order.

In cell biology, Protein kinase A ( PKA ) refers to a family of enzymes whose activity is dependent on cellular levels of cyclic AMP ( cAMP ).

Protochlorophyllide is a precursor to the production of a chlorophyll a molecule, or a light-independent process driven by other enzymes, to form a cyclic ring, and the reduction of another ring in the structure.

Secondary messenger systems can be synthesized and activated by enzymes, like the cyclases that synthesize cyclic nucleotides, or by opening of ion channels to allow influx of metal ions, like Ca < sup > 2 +</ sup > signaling.

All classes of AC catalyze the conversion of ATP to 3 ', 5 '- cyclic AMP ( cAMP ) and pyrophosphate.

Although PDE2 can hydrolyze both cyclic nucleotides, binding of cGMP to the regulatory GAF-B domain will increase cAMP affinity and hydrolysis to the detriment of cGMP.

These channels are also sensitive to the cyclic nucleotides cAMP and cGMP, which alter the voltage sensitivity of the channel ’ s opening.

For example, cyclic nucleotides can relax arterial smooth muscle without reductions in crossbridge phosphorylation, a process termed force suppression.

The cyclic nucleotides ( cGMP and cAMP ) produced by these cyclases activate Protein Kinase G and Proten Kinase A and phosphorylate a number of proteins.

Cyclic nucleotide-gated ion channels or CNG channels are ion channels that function in response to the binding of cyclic nucleotides.

Their function can be the result of a combination of the binding of cyclic nucleotides ( cGMP and cAMP ) and either a depolarization or a hyperpolarization event.

Before their discovery, it was thought that cyclic nucleotides played a role in phosphorylation.

They are directly activated by cyclic nucleotides, and approximately 4 cyclic nucleotides are needed to activate each channel.

The steep concentration between CNG channels and ligand concentration shows that at least two or three cyclic nucleotides are needed.

Binding affinity means how tightly cyclic nucleotides bind to the channel.