Alanine substitution Amino Acid Motifs Amino acids Antagonistic effects Comparative sequence analysis Cytoplasmic juxtamembrane Enzymes Fruits Lycopersicon esculentum Mutagenesis, Site-Directed Mutation Nicotiana tabacum Phosphorylation Phosphorylation sites Plant Proteins Plants (botany) Polarized cell growth Pollen Tube Protein Kinases Receptor-like kinase Site directed mutagenesis Tubes (components) alanine amino acid substitution article cell surface receptor controlled study enzymology gene overexpression genetics