Short forms of membrane receptors: Generation and role in hormonal signal transduction

This review highlights the generation of various types of short forms of membrane hormonal receptors and the mode of regulation of their tissue-specific patterns. The short forms of membrane receptors are classified on the basis of localization of missing functional fragments. The review provides examples of tissues for which expression of short forms may serve as a marker of changes of ontogenetic stage, physiological state, or the development of pathological process. The short forms of receptors are shown to participate in determining tissue-specificity and efficacy of hormonal signal transduction, as well as in transport of hormones within cell, through physiological barriers, and in blood circulation. Peculiarities of signal transduction pathways for short receptor forms and potential physiological significance of these forms are analyzed. It is concluded that the ratio of long and short receptor forms may serve as a key marker of dynamic changes of differentiation stage and alterations of metabolic and proliferative activity of tissues under normal and pathologic conditions, and thus to be an important indicator of therapeutic effect for many pathological processes.