Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

A post-import pathway for protein targeting to chloroplast inner membrane

Ming Li, University of Massachusetts Amherst


The chloroplast envelope plays critical roles in the synthesis and regulated transport of key metabolites, including intermediates in photosynthesis and lipid metabolism. Despite this importance, the biogenesis of the envelope membranes has not been investigated in detail. To identify the determinants of protein targeting to the inner envelope membrane (IM), I investigated the targeting of the nucleus-encoded integral IM protein, atTic40. I found that pre-atTic40 is imported into chloroplasts and processed to an intermediate size (int-atTic40) before insertion into the IM. Int-atTic40 is soluble and inserts into the IM from the internal stromal compartment. I also show that atTic40 and a second IM protein, atTic110, can target and insert into isolated IM vesicles in vitro. These in vitro studies are further supported by in vivo evidence showing pre-atTic40 directly engineered into the chloroplast genome and expressed within chloroplasts can efficiently target to the inner envelope membrane. Taken together, my experiments are consistent with a "post import" mechanism in which the IM proteins are first imported from the cytoplasm and subsequently inserted into the IM from the stroma.

Subject Area

Cellular biology

Recommended Citation

Li, Ming, "A post-import pathway for protein targeting to chloroplast inner membrane" (2008). Doctoral Dissertations Available from Proquest. AAI3336950.