Auxin plant hormones regulate a number of different processes involved in the growth and development of plants. In response to auxin are rapid changes occurring at the level of the cell membrane and changes in gene expression . Understanding the molecular principles of operation of auxin is essential to identify the hormone receptor . The variety of physiological processes regulated by auxin indicates the possibility of the operation of several independent mechanisms of auxin perception . Currently, it is assumed that the hormone involved in the perception of two receptors : auxin -binding protein ( ABP1 ) , with a known structure but still difficult to define the physiological functions and the auxin transport inhibitor protein ( TIR1 ) involved in auxin -induced gene expression. ABP1 mediates the early responses to auxin occurring at the level of the cell membrane. It also operates in the growth and cell division . Intracellular receptor is a component of a multimeric TIR1 ubiquitin ligase complex and occurs in the nucleus. This protein represents a new type of receptor that regulates the expression of genes dependent on the poliubikwitynację auxin , and then the degradation of a transcription repressor protein . The paper presents the progress made in recent years in the study of molecular structure , binding site and activity of auxin receptors .