Plants contain highly divergent actin isovariants

Abstract

Actin protein isovariants have been identified in animals with distinct cytoplasmic or muscle specific patterns of expression. Analysis of vascular plant actin gene sequences suggests that an even greater diversity should exist within the plant actin protein families, but previous studies on plant proteins have not demonstrated the presence of multiple actin isovariants. Antibodies recognizing a conserved amino-terminal plant actin peptide, a family of plant actin peptides from a variable region, and two monoclonal antibodies to conserved epitopes within animal actins were used to identify isovariants of soybean actin resolved by two-dimensional isoelectric focusing (IEF) sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Approximately six to eight actin isovariants with pI values ranging from 5.1 to 5.8 have been identified from soybean hypocotyls, stems, leaves, and roots with varying amounts of most isovariants present in all four organs. Acidic isovariants were present in much higher levels in leaves and stems. Antisera with lambda-class actin specificity detected a subset of three isovariants in all organs examined. One monoclonal and one antipeptide antisera are shown to react well with a wide variety of plant actin isovariants. Similar patterns of actin isovariants were detected in the distant angiosperms, Arabidopsis, petunia, and maize. It is likely that many of these diverse classes of isovariants have been preserved throughout vascular plant evolution and reflect the ancient diversity within plant actin gene families. The extreme difference among isovariants implies the presence of a complex actin-based cytoskeletal system in plants.

Molecular cloning and characterization of profilin from tobacco (Nicotiana tabacum): increased profilin expression during pollen maturation

“…According to the densitometrical analysis of the bands, mature pollen seems to contain more profilin than actin which seems not only to be due to the specificity of the antibody. It was also noted that the actin bands in pollen, leaves and seeds migrated at slightly different molecular weight which is likely explained by the expression of different actin isoforms in the tissues [28]. During early stages of pollen development no profilin was detected, whereas in mature pollen large amounts of profilin were found (Fig.…”

Immunocytochemical localisation of actin and profilin in the generative cell of angiosperm pollen: TEM studies on high-pressure frozen and freeze-substitutedLedebouria socialis Roth (Hyacinthaceae)

“…19A) to recognise proteins of approximately 46 kDa in L. socialis flower (P) and leaf (L) extracts. The fact that actin in B flowers and leaves migrated at slightly different molecular weight is probably explained by the expression of different actin isoforms in the tissues (McLean et al 1990). Additional bands at higher molecular weight may be due to the detection of profilactin complexes, whereas binding to components of a lower molecular weight could be due to proteolysis in the extracts (see Koropp and Volkmann 1994 and references therein).…”

Subcellular Targeting of Methylmercury Lyase Enhances Its Specific Activity for Organic Mercury Detoxification in Plants

“…Protein extracts and western blots were prepared as described previously for MerB (Bizily et al, 2000) or with a direct SDS protein extraction procedure (McLean et al, 1990). Equal amounts of protein for all CW-merB and ER-merB lines and merA negative control plant lines were resolved on SDS-PAGE, transferred to membranes, and reacted with antibodies.…”