1.
Jens Peter Andersen, DMSc, Professor
E-mail: jpa@biomed.au.dk
Web site: http://pure.au.dk/portal/da/jpa@fi.au.dk
 +45 20 43 43 62
 Aarhus University, Department of Biomedicine
Ole Worms Allé 4, bldg. 1160, room 315
8000 Aarhus C, Denmark
DEPARTMENT OF BIOMEDICINE
HEALTH
AARHUS UNIVERSITY
To whom this may concern March 19, 2016
Reference for Masumeh Chavosi (Massi)
Massi has been employed as lab technician in my lab at Aarhus University for two years. We are a
research group at the Department of Biomedicine working with membrane transport proteins, and
her project was the transport mechanism of phopholipid flippases. When she started in the lab,
she had a lot of general expertise as technician, but no specific skills relating to this topic except
for handling of cell cultures. However, she learned rapidly, and today she masters very well all the
techniques descibed below.
The focus of the project was to examine the function of mutant flippase proteins. Mutations are
introduced in the cDNA encoding the flippase by site‐directed mutagenesis. The next step is to
transfect HEK293T cells in culture with the mutant cDNA to obtain transient expression. Then the
plasma membranes are harvested by centrifugation and solubilized in detergent, and the flippase
protein is purified by immunoaffinity chromatography, taking advantage of a C‐terminal tag that
reacts with a specific antibody bound to immunoaffinity matrix. The eluted purified protein is
finally reconstituted in lipid vesicles by dialysis to remove detergent. To characterize the function
of the product, the rate of ATP hydrolysis is measured under various conditions using a
colorimetric microplate method. The rates of phosphorylation and dephosphorylation are
determined using radio labeled [γ‐32
P]ATP, separating the labeled protein by gelelectrophoresis.
Massi has also learned to perform rapid‐kinetic experiments for measurement of reaction rates in
the millisecond time range using BioLogic QFM‐5 quenched flow equipment.
Particularly the functional measurements require high precision to determine the correct affinities
for lipids in activation of ATP hydrolysis and dephosphorylation as well as maximal rate. Massi is
very accurate and precise in her work, and the data she obtains can be trusted. She is furthermore
a nice and friendly person, helpful to colleagues and interacting in a highly productive way with
the students in the lab.
I have been very satisfied with Massi, and I will miss her both personally and as the very efficient
working power she has been in the lab. Nevertheless, I understand and respect her decision to
move from Aarhus to stay with her husband in Seattle.
Sincerely