2024年12月25日 (三) 03:06 长河

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Figure 17–29 The centrosome cycle. In
early G1, the centrosome consists of two
centrioles linked by a protein tether, as
well as associated pericentriolar material
for nucleation of microtubules (light green).
One centriole, the mature parent, carries
protein appendages required for certain
centrosome functions. Upon entry into
the cell cycle, G1/S-Cdk and Plk4 initiate
centriole duplication, whereby a new
centriole (procentriole) is assembled at
a single site on the side of each parent
centriole (yellow dots). The elongation
of the procentrioles is usually completed
in G2. The two centriole pairs remain
close together in a single centrosomal
complex until entry into mitosis, when the
protein kinases M-Cdk, Plk1, and other
regulators trigger numerous changes: the
tether between centrosomes is removed,
the immature parent centriole acquires
appendages (centriole maturation), the
pericentriolar material expands to enable
more microtubule nucleation (centrosome
maturation), and the centrosomes
separate, forming a new spindle between
them. After the completion of mitosis, the
two centrioles in each centrosome detach
(centriole disengagement), and the new
centriole acquires pericentriolar material
(centriole-to-centrosome conversion).
These two processes are required for
centriole duplication in the subsequent cell
cycle; thus, progression through mitosis is
required for duplication, helping to ensure
that centrioles (and centrosomes) duplicate
only once per cell cycle

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2024年12月25日 (三) 03:06 长河