BIO254:Pacemaker

Due Date: 11/20

Definition

A pacemaker is a rhythm generator. Biological pacemakers drive many time-dependent processes in organisms, including heart rate, cell division in embryogenesis, .

Artificial pacemakers

Artificial pacemakers are used to rescue patients with deficient pacemakers, for example when the sinus node of the heart does not function correctly. Genetically engineered pacemakers may begin to replace microelectronic pacemakers (Boink, 2006).

an oscillator, or rhythm generator.  Biological pacemakers can be in a single cell, but typically involve many cells.  The periods of biological pacemakers span a large range. 

References

Med Biol Eng Comput. 2006 Oct 18; [Epub ahead of print]

Gene therapy to create biological pacemakers.

Boink GJ, Seppen J, de Bakker JM, Tan HL.

Heterotrimeric G proteins

Heterotrimeric G proteins are comprised of three subunits -- α, β and γ -- that exist as a complex (G_αβγ) in the GDP-bound state but dissociate (into G_α and G_βγ) upon the release of GDP and binding of GTP. G_α contains the GDP/GTP binding site and GTPase activity (Fig. 1). The C-terminus of G_α gives the G protein affinity for specific membrane-bound GPCRs (see below).

Figure 1. Image from (Milligan, 2006). Some parts have been removed for clarity. GDP is shown in purple. The α subunit C-terminus residues, shown in blue, convey GPCR specificity. The N-terminus helix, shown in red, is required for binding of G_αto the other subunits.

A pacemaker (in the context of NBIO 254) is a biological clock, or in other words a rhythm generator in an organism.

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