BIOL 467 Lecture Notes - Lecture 5: Cyclin H, Cyclin B, Cyclin D
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The component that will bind to the cdk and help activate the cdk. Cdks o(cid:374) their o(cid:449)(cid:374) (cid:373)a(cid:455) (cid:271)e (cid:272)o(cid:374)stituti(cid:448)el(cid:455) e(cid:454)pressed (cid:271)ut (cid:272)a(cid:374)(cid:374)ot (cid:271)e a(cid:272)ti(cid:448)e u(cid:374)til the(cid:455)"re part(cid:374)ered with a particular cyclin. A lot of specificity is coming from the cyclin. Every organism has either an equivalent or homologous cyclin, or not so homologous (sequences are degenerate) but equivalent cyclins mediating different stages. Some of the early study on cyclins were done on mitotic cyclins zedapus extracts during embryonic divisions (only cycling between synthesis and m phase) Typifies how the patterning of cyclin b expression and degradation closely matches the increases in mitotic index. C(cid:455)(cid:272)li(cid:374) b e(cid:454)pressio(cid:374) rises, a(cid:374)d that"s see(cid:374) (cid:271)(cid:455) the (cid:373)ost i(cid:374)te(cid:374)se (cid:271)a(cid:374)ds (cid:894)(cid:1010)(cid:1004)(cid:895) Cyclin b degradation = mitotic index also drops. Unique feature is that they contain destruction boxes crucial for the degradation. Poly-ubiquitination is acting as the signal for ultimate degradation by the proteasome occurring through the apc complex.
