Molecular characterization of cDNAs encoding G protein alpha and beta subunits and study of their temporal and spatial expression patterns in Nicotiana plumbaginifolia Viv.
We have isolated cDNA sequences encoding alpha and beta subunits of potential G proteins from a cDNA library prepared from somatic embryos of Nicotiana plumbaginifolia Viv. at early developmental stages. The predicted NPGPA1 and NPGPB1 gene products are 75-98% identical to the known respective plant alpha and beta subunits. Southern hybridizations indicate that NPGPA1 is probably a single-copy gene, whereas at least two copies of NPGPB1 exist in the N. plumbaginifolia genome. Northern analyses reveal that both NPGPA1 and NPGPB1 mRNA are expressed in all embryogenic stages and plant tissues examined and their expression is obviously regulated by the plant hormone auxin. Immunohistological localization of NPGPalpha1 and NPGPbeta1 preferentially on plasma and endoplasmic reticulum membranes and their immunochemical detection exclusively in microsomal cell fractions implicate membrane association of both proteins. The temporal and spatial expression patterns of NPGPA1 and NPGPB1 show conformity as well as differences. This could account for not only cooperative, but also individual activities of both subunits during embryogenesis and plant development.
Kaydamov
C
C
Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, D-06466, Gatersleben, Germany.
Tewes
A
A
Adler
K
K
Manteuffel
R
R
D000595:Amino Acid Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010947:Plants, Toxic; D011523:Protoplasts / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds; D016415:Sequence Alignment; D014026:Nicotiana / Q000737:chemistry / Q000196:embryology / Q000235:genetics*
D018076:DNA, Complementary; D012333:RNA, Messenger; D019204:GTP-Binding Proteins