BIO409/509 Cell and Molecular Biology

subject: Pre-Med Social this Thursday There will be a social hour for pre-med students this Thursday, April 28th, from 4:00 to 5:00 PM in the Fishbowl (room 153 Science Building). The purpose is to say hello to other pre-med students and network to gain info about the pre-med pathway. We'll be hosting Dr. Fred Fridman. Fred graduated from USM a few years ago and has just returned to begin practicing medicine at New England Rehabilitation Hospital and Maine Medical Center. Please come to say hello. We have a great group of pre-meds at USM and there are probably some you don't know yet. Bring food to share if you'd like. That would be great. Thanks!

BIO409/509 Cell and Molecular Biology The final exam will cover material from class since the second exam plus: Ch 8 RNA Ch 9 proteins Ch 10 nucleus Ch 11 protein sorting and transport (probably) Ch 13 cytoskeleton

Protein Synthesis, Processing, and Regulation 9

Figure 9.9 Overview of translation

Figure 9.30 The role of signal sequences in membrane translocation

Figure 9.23 Action of chaperones during translation

Figure 9.25 Sequential actions of chaperones

Figure 9.28 The action of protein disulfide isomerase

Post-translational regulation is a term not often used Post-translational modifications are a subset of the above. This term is often used.

Figure 9.33 Synthesis of N-linked glycoproteins

Figure 9.31 Proteolytic processing of insulin

Figure 9.38 Structure of a GPI anchor

Regulation of Protein Function Cells can regulate the amounts and the activities of their proteins. Three mechanisms: Regulation by small molecules Phosphorylation and other modifications Protein-protein interactions

Figure 9.43 Modification of proteins by small molecules (Part 1)

Figure 9.44 Modification of proteins by ubiquitin

Figure 9.46 The ubiquitin-proteasome pathway

Figure 9.47 Cyclin degradation during the cell cycle

Figure 9.48 Autophagy

Figure 9.41 Protein kinases and phosphatases

Changes in sensitivity of target cells to estrogen include changes in the estrogen receptor and more.

The Nucleus 10

10 The Nucleus The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm The Organization of Chromosomes Nuclear Bodies

Introduction The nucleus is the main feature that distinguishes eukaryotic from prokaryotic cells. It houses the genome, and thus is the repository of genetic information and the cell’s control center. Separation of the genome from the site of mRNA translation plays a central role in eukaryotic gene expression.

The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm The nuclear envelope separates the nuclear contents from the cytoplasm. It controls traffic of proteins and RNAs through nuclear pore complexes, and plays a critical role in regulating gene expression.

The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm The outer membrane is continuous with the endoplasmic reticulum (ER). The space between inner and outer membranes is directly connected with the lumen of the ER. The inner membrane has integral proteins, including ones that bind the nuclear lamina.

Figure 10.1 The nuclear envelope (Part 1)

Figure 10.1 The nuclear envelope (Part 2)

Figure 10.1 The nuclear envelope (Part 3)

Figure 10.4 Lamin assembly

Figure 10.3 Electron micrograph of the nuclear lamina

The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm Mutations in lamin genes cause several inherited tissue-specific diseases. The bases of the pathologies in each of these diseases is still unclear.

Molecular Medicine, Ch. 10, p. 371

Figure 10.5 The nuclear lamina

Figure 10.6 Molecular traffic through nuclear pore complexes

The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm Electron microscopy shows pore complexes have eight subunits organized around a large central channel.

Figure 10.7 Electron micrograph of nuclear pore complexes

The Nuclear Envelope and Traffic between the Nucleus and the Cytoplasm Eight spokes are connected to rings at the nuclear and cytoplasmic surfaces. The spoke-ring assembly surrounds a central channel. Protein filaments extend from the rings, forming a basketlike structure on the nuclear side.

Figure 10.8 Model of the nuclear pore complex

Figure mRNA export