title: New microsome-associated HT-family proteins from Nicotiana respond to pollination and define an HT/NOD-24 protein family.
abstract: HT-family proteins have been identified in Nicotiana, Solanum, and Petunia. HT-B-type proteins are implicated in S-RNase-based self-incompatibility, but the functions of other family members are unknown. Screening for cDNA sequences with an expression pattern similar to HT-B in Nicotiana alata revealed a new group of small HT-family proteins, designated HT-M. HT-M proteins resemble HT-B in several respects: their pistil-specific expression pattern is indistinguishable from HT-B, they pellet with a microsome fraction, and their abundance decreases after pollination. Unlike HT-B, there is no S-specificity to this response, and RNAi experiments show that HT-M proteins are not necessary for self-incompatibility. Identification of a third group of pistil-specific HT-family proteins helps better define the characteristics of the family and allowed identification of putative new family members. By searching the databases with only the most conserved HT-family sequence elements, the signal sequence and cysteine motifs, we identified nodulin-24-like proteins and several small glycine-rich proteins as putative HT-family members. Like HT-M and HT-B, nodulin-24 is membrane associated. We propose that the conserved features in HT-family proteins are important for targeting or modification and refer to the broader family that includes both HT- and nodulin-24-like proteins as the HT/NOD-24-family.
authors.affiliation: Department of Biochemistry, University of Missouri, MI, USA.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kondo
authors.forename: Bruce
authors.initials: B
authors.lastname: McClure
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D035264:Flowers / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008861:Microsomes / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D009928:Organ Specificity / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000502:physiology; D054817:Pollination / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000235:genetics / Q000502:physiology*
chemical_list: D010940:Plant Proteins