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Mitochondrial porin of Neurospora crassa: cDNA cloning, in vitro expression and import into mitochondria.
Author(s) -
Kleene R.,
Pfanner N.,
Pfaller R.,
Link T. A.,
Sebald W.,
Neupert W.,
Tropschug M.
Publication year - 1987
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1987.tb02553.x
Subject(s) - neurospora crassa , neurospora , biology , humanities , genetics , philosophy , gene , mutant
cDNA encoding porin of Neurospora crassa, the major protein component of the outer mitochondrial membrane, was isolated and the nucleotide sequence was determined. The deduced protein sequence consists of 283 amino acids (29,979 daltons) and shows sequence homology of around 43% to yeast porin; however, no significant homology to bacterial porins was apparent. According to secondary structure predictions, mitochondrial porin consists mainly of membrane‐spanning sided beta‐sheets. Porin was efficiently synthesized in vitro from the cDNA; this allowed us to study in detail its import into mitochondria. Thereby, three characteristics of import were defined: (i) import depended on the presence of nucleoside triphosphates; (ii) involvement of a proteinaceous receptor‐like component on the surface of the mitochondria was demonstrated; (iii) insertion into the outer membrane was resolved into at least two distinct steps: specific binding to high‐affinity sites and subsequent assembly to the mature form.