MICR 221 Lecture Notes - Lecture 12: Atp-Binding Cassette Transporter, Membrane Fusion Protein, Signal Peptidase

• School: Queen's University
• Department: Microbiology and Immunology
• Course: MICR 221
• Professor: Mixed

Document Summary

All protein secretion pathways require energy in the form of atp. For both gram negative and gram positive, the major pathway for transporting proteins across the cm is the sec dependent pathway. 7 secretion pathways have been identified in gram negative bacteria. Type 2 and 4 transport proteins across om as they are first translocated across plasma membrane by sec dependent pathway. Type 4 pathway usually functions independent of the sec pathway. Most (but not all) proteins to be secreted from the cell are made with n-terminal signal peptides. They are cleaved during export across the cm by signal peptidases. There is no sequence homology but there are 3 conserved areas in signal peptides: *2) the hydrophobic central region (h region) ie) leucine and isoleucine. *3) c-terminal containing hydrophilic region (c region) containing spase processing signals. Ie) alanine and serine are recognition sites for signal peptidases. A hydrophobic core spans the cm exposing cleavage sites on the periplasmic side.