Presentation on theme: "Chapter 26 Protein Sorting. Chapter Objectives Understand the pathways of cotranslational processing of proteins – ER, Golgi, Plasma membrane, Lysosomes."— Presentation transcript:
Chapter Objectives Understand the pathways of cotranslational processing of proteins – ER, Golgi, Plasma membrane, Lysosomes Understand the pathways of posttranslational processing of proteins – Mitochondria, Peroxisomes, Nucleus
Overview Cytoplasmic proteins Mitochondria, peroxisome, or nuclear proteins Extracellular, lysosomal, ER proteins
To the Peroxisome Peroxisomes are thought to be artifact organelles – Oxidation reactions Without producing energy – Break down lipids – No synthesis of proteins – PTS1 and PTS2 are signals to import proteins PTS1 has a c-terminal SKL tripeptide
To the Nucleus Transport proteins – Proteins and RNA are leaving the nucleus – Proteins are trying to get into the nucleus – Some proteins are really big Nuclear Pore Complex (nucleoporin) – Very big allows diffusion of up to 40,000 Da proteins – Larger proteins must be accepted by complex
Big Protein Transport NLS (nuclear localization signal) – Very positive charge PKKKRKV KRxxxxxxxxxxPAAIKKAGQAKKKK NES (nuclear export signal) Some proteins go both ways – Heteroribonucleoprotein complex (hnRNP) Shuttles mRNA out of nucleus Returns to pick up more 38 amino acid signal sends it both directions
Entropy and Transport to Nucleus Not energy mechanism innate to nucleoporin Uses small GTP/GDP binding protein Ran
Your consent to our cookies if you continue to use this website.