Block2 5.microtubules I

Front 1

Microtubules: Function

Back 1

1. Mitotic spindle.
2. Interphase cellular structure.
3. Cellular structure and transport.
4. Movement: cilia and flagella.

Front 2

1.Alpha Tubulin
2.Beta Tubulin

Back 2

1.Always bound to GTP; never hydrolyzes it. At (-) of microfilament
2.Can bind either GTP or GDP

They always form dimers, which form protofilaments, 13 of which form a full microtubule

Front 3

Taxol

Back 3

Stabilizes microtubules by fitting into a site on beta tubulin;
used to treat cancer

Front 4

Microtubule-
1.Singlet
2.Doublet
3.Triplet

Back 4

1.13 protofilaments in a tube
2. 13,10: Cilia and flagella
3. 13,10,9: Basal bodies, centrioles

Front 5

Critical Concentration

Back 5

At [Critical] (or above), microtubule polymerization occurs. The Cc is lower at plus end than at minus, making the plus end more dynamic and considered the growing end. Polymerization is dependent on substrate (dimer) pool
and status of GTP/GDP status of β-tubulin.

Front 6

MAP2

Back 6

Microtubule stabilizing protein. Has binding domain that is positively charged; it binds the negatively charged tubulin. Has a projection domain that is negatively charged and juts outward, keeping a distance between it and other tubules. Phosphorylation introduces negative charge and destabilizes interactions

Front 7

Kinesin-13 Family

Back 7

Microtubule destabilizer: Bind (+)
end and curve
protofilaments, promoting
catastrophe.

Front 8

Op18/Stathmin

Back 8

Microtubule destabilizer: Bind two
dimers and bend similar to
Kinesin-13 family. May
also enhance GTP
hydrolysis.

Front 9

Katanin

Back 9

Microtubule destabilizer: Severs and
breaks microtubules,
exposing GDP caps →
catastrophe.

Front 10

Colchicine

Back 10

Destabilizer: binds/sequesters dimer pool ([dimer]<Cc). Prevent
polymerization and promotes catastrophe and rapid depolymerization.
Historically used to reduce WBC migration and inflammation in Gout.

Front 11

Vinblastine, Podophyllotoxin, Nocodazole

Back 11

stops spindle formation, for cancers

Front 12

Tau

Back 12

Alzheimer's. It is an abnormal hyper-phosphorylation of Tau that causes its abnormal shape change. Tangles are actually from aggregates of crappy Tau's. Tau makes tangles. APP makes plaques.

Front 13

Pin-1

Back 13

Pin1 promotes the trans form of both pAPP and pTau = less phosphorylation, and this is protective, resulting in less plaques and tangles. APP makes plaques. Aβ42 plaques and Tau tangles
accelerated if PhosphoThreonine–
Proline motif has proline in cis
conformation.