The outer membrane from mitochondria of etiolated maize epicotyls was
isolated by a shrinkage-swelling-shrinkage procedure. The polypeptide
pattern of the outer membrane revealed five porin isoforms (M(r)s 33 0
00-34 000) in the pi region between 6.7 and 7.5. The phospholipid comp
osition of the outer membrane was characterized by avery high phosphat
idylcholine/phosphatidylethanolamine ratio, a significant amount of ph
osphatidylinositol and a low double bond index value. Analysis of mole
cular species by HPLC showed that 16:0/18:2 molecules of phosphatidylc
holine and phosphatidylethanolamine were more specifically associated
with the outer membrane, while 18:2/18:2 molecules were preferentially
localized in the inner membrane. The results are discussed in relatio
n to the biogenesis of mitochondrial lipids. Copyright (C) 1996 Publis
hed by Elsevier Science Ltd