©CMBI 2006 Molecular motors At the organism – population level, motors are needed to transfer materials. At the organelle – organ level, motors are needed to transfer material and information.

©CMBI 2006 Slides borrowed from:

©CMBI 2006 Motors

©CMBI 2006 Kinesin - Dynein Kinesin: Most members of the kinesin family of motor proteins walk along microtubules away from the centrosome. Dynein: The dyneins walk along microtubules toward the centrosome).

©CMBI 2006 The Tubulin Autobahn In the cell itself, microtubules are formed in an area near the nucleus called the "aster". This is also called the Microtubule Organizing Center (MTOC). Microtubules are polar with a plus end (fast growing) and a minus end (slow growing). Usually the minus end is the anchor point in the MTOC. In this figure, the plus end is shown to the left by the numerous tubulin dimers. This is the end that carries the GTP molecules which may be hydrolyzed to GDP.

©CMBI 2006 Actin - Myosin

©CMBI 2006 Perpetual motion - A/GTP

©CMBI 2006 G proteins do it with GTP

©CMBI 2006 Cholesterol transport

©CMBI 2006 Information transfer Information flows through our body in many different ways. One method is to send out messengers (hormones) that can be recognized by other cells or organs. GPCRs and nuclear receptors are examples of receptors for this type of information.

©CMBI 2006 Rule 1 First rule of sequence analysis: If a residue is conserved, it is important.

©CMBI 2006 Rule 2 Second rule of sequence analysis: If a residue is very conserved, it is very important.

©CMBI 2006 Sequence Entropy 20 E i =  p i ln(p i ) i=1

©CMBI 2006 Sequence Variability Sequence variability is the number of residues that is present in more than 0.5% of all sequences.

©CMBI 2006 Entropy - Variability Variability is result of evolution. Entropy is the protein’s break on evolutionary speed.

©CMBI 2006 GPCR Entropy - Variability 11 Red 12 Orange 22 Yellow 23 Green 33 Blue

©CMBI 2006 GPCR Location 11 Red 12 Orange 22 Yellow 23 Green 33 Blue

©CMBI 2006 Ras Entropy - Variability

©CMBI 2006 Ras Location 11 Red 12 Orange 22 Yellow 23 Green 33 Blue

©CMBI 2006 Enzyme active site