A protein kinase that is specific to the amino acids serine and threonine is known as a mitogen-activated protein kinase (MAPK or MAP kinase; also known as a serine/threonine-specific protein kinase).
<h3>Mitogen-activated protein kinase :</h3>
A small number of cell surface receptors can ultimately generate a large intracellular response due to activation of kinase cascades.
In order to trigger an appropriate physiological response, such as cellular proliferation, differentiation, development, inflammatory reactions, and death in mammalian cells, MAPK pathways relay, amplify, and integrate information from a variety of stimuli.
Tyrosine phosphorylation, specifically numerous tyrosines on each RTK in the dimer, is how cross-linking triggers the tyrosine kinase activity in these RTKs. The term "cross-phosphorylation" refers to this action.
The activation of a MAPKKKK or MAPKKK by stimulation of plasma membrane receptors is the initial stage of signal transduction. The MAPKKK then phosphorylates two serine or threonine residues in the S/T-X5-S/T (X is any amino acid) motif of its activation loop, activating a downstream MAPKK.
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SPJ4
In geology, a key bed (syn marker bed) is a relatively thin layer of sedimentary
rock that is readily recognized on the basis of either its distinct
physical characteristics or fossil content and can be mapped over a very
large geographic area.[1]
As a result, a key bed is useful for correlating sequences of
sedimentary rocks over a large area. Typically, key beds were created as
the result of either instantaneous events or (geologically speaking)
very short episodes of the widespread deposition of a specific types of sediment. As the result, key beds often can be used for both mapping and correlating sedimentary rocks and dating them. Volcanic ash beds ( and bentonite beds) and impact spherule beds, and specific megaturbidites
are types of key beds created by instantaneous events. The widespread
accumulation of distinctive sediments over a geologically short period
of time have created key beds in the form of peat beds, coal beds, shell beds, marine bands, black in cyclothems, and oil shales. A well-known example of a key bed is the global layer of iridium-rich impact ejecta that marks the Cretaceous–Paleogene boundary (K–T boundary). Please let me know if it works.
Answer:
The Mid-Atlantic Ridge runs down the center of the Atlantic Ocean. ... The rift valley is 1 to 3 km deep, about the depth and width of the Grand Canyon. In contrast, the East Pacific Rise spreads fast at rates of 6 to 16 cm per year (more than 20 cm per year in the past).
