Is _ actin a regulator of amino acid transport?.
Lin, Guorong, J. McCormick, and Rose M. Johnstone.
Department of Biochemistry, McGill University, 3655 Drummond St.,
Montr[acute]eal, Que. Canada H3G 1Y6, Telephone No. (514) 398-7273;
Fax No. (514) 398-7384
APStracts 2:0432C, 1995.
A mutated yeast cell line incapable of growth in minimal medium with
proline as sole nitrogen source was restored to normal growth by
transfection with a cDNA from mouse Ehrlich cells. The cloned cDNA
(E51) was found to be 90% homologous to _ actin. Upon transfection
with E51 cDNA, both AIB and proline uptake in the mutated yeast were
increased, particularly at pH5. The expression of the same E51 cDNA
also enhanced amino acid uptake in Xenopus oocytes, after injection
into Xenopus nuclei. A mutated mammalian lymphocyte cell line (GF
-17), deficient in A system transport, also showed increased Na+
-dependent transport after transfection with E51 cDNA. Whereas the
mock transfected GF-17 cells failed to grow in the selection medium,
the transfectants with E51 cDNA grew better than the untransfected
cells. The data are consistent with the conclusion that expression of
E51 cDNA can modify inactive, endogenous amino acid transporters
permitting substantial amino acid uptake in cells deficient in amino
acid transporter(s) and permit rapid cell growth. The data suggest
that the _ actin-like protein coded for by E51 cDNA may play a
significant regulatory role in amino acid transport.
Received 13 June 1995; accepted in final form 22 November1995
APS Manuscript Number C337-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95