Receptor kinase involved in the perception of C-terminally encoded plant signaling peptide (CEP) and subsequent regulation of root and shoot development (PubMed:25324386). Required for xylem and phloem cell files morphology and organization, probably by preventing ectopic lignification in phloem cells (PubMed:21853254). Together with CEPR2, mediates systemic nitrogen (N)-demand signaling upon the perception of root-derived peptides (e.g. CEP1) via the up-regulation of genes involved in N uptake and assimilation pathways (PubMed:25324386). Regulates positively lateral root initiation and development; probably repressed by the signaling peptide CEP5 (PubMed:27296247). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts with the root-derived peptides CEP1, CEP3 and CEP5. Expressed in the vasculature, especially in phloem and procambium regions, of stems, leaves, cotyledons, sepals, pedals, pedicels, hypocotyls and roots (in primary and lateral roots, but not in root tips) (PubMed:21853254, PubMed:25324386). Expressed in the root from the basal meristem onward. Present in the phloem pole pericycle and in the adjacent phloem (PubMed:27296247). Expressed in the vasculature, especially in phloem and procambium regions, from the mature embryo stage through the adult plant (PubMed:21853254). Excluded from early stages of lateral root development (PubMed:27296247). Defects in vascular organization and phloem differentiation in inflorescence stems, characterized by aberrant accumulation of highly lignified cells, typical of xylem or fiber cells, within the phloem, and phloem cells sometimes adjacent to xylem cells. Malformed vascular cells files, probably due to defects in oriented cell divisions or cell morphology, and leading to both phloem specification defects and disrupted xylem vessel formation. Short inflorescence stems and increased anthocyanin accumulation in leaves (PubMed:21853254). Reduced total lateral root density, due to a reduction in stage I and II lateral root primordia and, to a lower extent, to fewer emerged lateral roots. Impaired sensitivity to CEP5 with respect to root growth regulation (PubMed:27296247). Growth retardation accompanied with nitrogen (N)-deficiency symptoms. Slight enhanced lateral root elongation in simple mutant. The double mutant cepr1 cepr2 is insensitive to CEP1 in a root growth regulation and exhibit pleiotropic phenotype characterized by pale-green leaves and enhanced lateral root elongation. At adult stage, smaller rosette leaves and shorter floral stems, accompanied by anthocyanin accumulation. Down-regulation of genes involved in N uptake and assimilation pathways (e.g. NRT1.1, NRT2.1 and NRT3.1) leading to impaired nitrate uptake activity. Altered systemic induction of genes involved in N uptake and assimilation pathways in N-depletion conditions (PubMed:25324386). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.