D103 - Lecture 7 - Microtubules.docx

2 Pages
Unlock Document

Biological Sciences
Grant Mac Gregor

A.Microtubule a. Alpha and beta tubulin i. Are not found free in the cytosol ii. Always need to be a dimer b. Alpha tubulin i. GTP is bound- never hydrolyzed b. Beta tubulin i. GTP bound here can be hydrolyzed to GDP b. 13 polar protofilaments form a microtubule c. GTP on beta tubulin is hydrolyzed slowly i. GTP cap 1. The alpha/beta dimers are still bound to GTP at the + end 2. Adding too fast 3. Needed for the microtubule to extend 4. NOT A CAPPING PROTEIN ii. GDP cap 1. Microtubule will depolymerize 2. Individual protofilaments are falling apart B.MT binding proteins a. Stathmin i. Sequestering protein, binds subunits b. Kinesin 13 i. Enhances disassembly at the plus end ii. Catastrophe - disassembly b. Gamma-TuRC i. Related to tubulin ii. Nucleation factor at the minus end 1. Serves as a cap at the minus end b. XMAP215 i. Stabilizes plus end and accelerates assembly B.Microtubule Organizing Center (MTOC) a. Centrosome b. Nucleates and anchors MT at the minus end c. Gamma-tubulin is localized here B.Centrosome a. Centrioles are organized in triplets, 9 triplets b. Centrioles i. Not present in plants or fungi b. Gamma-tubulin = part of the gamma-TuRC proteins c. No branching d. JOB i. Interphase 1. Helps with cell polarity, organelle position, vesicle transport ii. Mitosis 1. Forms the bipolar mitotic spindle B.Centrosomes duplicated a. Centrosomes are duplicated once per cell cycle i. Duplica
More Less

Related notes for BIO SCI D103

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.