Transcription factor required for quiescent center cells specification and maintenance of surrounding stem cells, and for the asymmetric cell division involved in radial pattern formation in roots. Essential for both cell division and cell specification. Regulates the radial organization of the shoot axial organs and is required for normal shoot gravitropism. Directly controls the transcription of SCR, and when associated with SCR, of MGP, RLK, TRI, NUC and SCL3. Interacts with SCR, SCL23, JKD and MGP (PubMed:16640459, PubMed:17446396, PubMed:17785527, PubMed:18500650, PubMed:28211915). Interacts with SIEL (PubMed:21924907). Association to endosomes and intercellular movement of SHR rely on the interaction with SIEL (PubMed:25124761). Cytoplasm and nucleus in the stele (PubMed:11565032, PubMed:15498493). Restricted to the nucleus in adjacent cells (PubMed:11565032, PubMed:15498493). Localization to endosomes promotes the intercellular movement of SHR (PubMed:25124761). Expressed in the stele and the quiescent center. Not detected in the ground tissue cell lineage. The SHR protein moves from the stele to a single layer of adjacent cells, where it enters the nucleus. Expressed in the procambium during embryogenesis. Moves via plasmodesmata from the stele into the adjacent cell layer where it locates in the nucleus to controls SCR transcription and endodermis specification. Intact microtubules are required for cell-to-cell trafficking of SHR (PubMed:23294290). This intercellular movement is dependent upon the endosome localized protein SIEL (PubMed:21924907). It is necessary for normal patterning of the root (PubMed:19000160). Belongs to the GRAS family.