Isolation of a cDNA clone for spinach lipid transfer protein and evidence that the protein is synthesized by the secretory pathway

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Plant Physiology; (United States)

DOI:https://doi.org/10.1104/pp.95.1.164· OSTI ID:5715506

Bernhard, W R; Thoma, S; Botella, J; Somerville, C R ^[1]

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1. Michigan State Univ., East Lansing (United States)

A cDNA clone encoding a nonspecific lipid transfer protein from spinach (Spinacia oleracea) was isolated by probing a library with synthetic oligonucleotides based on the amino acid sequence of the protein. Determination of the DNA sequence indicated a 354-nucleotide open reading frame which encodes a 118-amino acid residue polypeptide. The first 26 amino acids of the open reading frame, which are not present in the mature protein, have all the characteristics of a signal sequence which is normally associated with the synthesis of membrane proteins or secreted proteins. In vitro transcription of the cDNA and translation in the presence of canine pancreatic microsomes or microsomes from cultured maize endosperm cells indicated that proteolytic processing of the preprotein to the mature form was associated with cotranslational insertion into the microsomal membranes. Because there is no known mechanism by which the polypeptide could be transferred from the microsomal membranes to the cytoplasm, the proposed role of this protein in catalyzing lipid transfer between intracellular membranes is in doubt. Although the lipid transfer protein is one of the most abundant proteins in leaf cells, the results of genomic Southern analysis were consistent with the presence of only one gene. Analysis of the level of mRNA by Northern blotting indicated that the transcript was several-fold more abundant than an actin transcript in leaf and petiole tissue, but was present in roots at less than 1% of the level in petioles.

• DOE Contract Number: AC02-76ER01338
• OSTI ID: 5715506
• Journal Information: Plant Physiology; (United States), Vol. 95:1; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
SPINACH
BIOLOGICAL PATHWAYS
AMINO ACID SEQUENCE
BIOLOGICAL FUNCTIONS
DNA-CLONING
DOGS
GENES
LIPIDS
MAIZE
MESSENGER-RNA
PROTEINS
ROOTS
TRANSCRIPTION
ANIMALS
CEREALS
CLONING
DNA HYBRIDIZATION
FOOD
GRAMINEAE
HYBRIDIZATION
LILIOPSIDA
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MAMMALS
MOLECULAR STRUCTURE
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PLANTS
RNA
VEGETABLES
VERTEBRATES
550200* - Biochemistry
551000 - Physiological Systems