Model for growth hormone receptor activation based on subunit rotation within a receptor dimer

Growth hormone is believed to activate the growth hormone receptor (GHR) by dimerizing two identical receptor subunits, leading to activation of JAK2 kinase associated with the cytoplasmic domain. However, we have reported previously that dimerization alone is insufficient to activate full-length GHR. By comparing the crystal structure of the liganded and unliganded human GHR extracellular domain, we show here that there is no substantial change in its conformation on ligand binding. However, the receptor can be activated by rotation without ligand by inserting a defined number of alanine residues within the transmembrane domain. Fluorescence resonance energy transfer ( FRET), bioluminescence resonance energy transfer (BRET) and coimmunoprecipitation studies suggest that receptor subunits undergo specific transmembrane interactions independent of hormone binding. We propose an activation mechanism involving a relative rotation of subunits within a dimeric receptor as a result of asymmetric placement of the receptor-binding sites on the ligand.

The use of email in a child and adolescent mental health service: are staff ready?

All staff members of a child and adolescent mental health service were invited to participate in a survey about the use of email. Sixty-two of the 105 staff members responded to the survey, a participation rate of 59%. Of the respondents, 32 were allied health staff, 10 were nurses, seven were administrative staff, six were medical staff, three were operational staff and four were acting in a combination of these roles. The respondents reported extensive work-related email usage and considered that they were confident in using email despite low levels of training. However, they did not feel that they understood the legal and ethical issues involved. Furthermore, there was limited incorporation of email into standard record keeping. The majority of respondents thought that increased use of email would lead to a greater workload, a consequence they considered would probably increase over time. Many commented on the quick and practical use of this medium, but were wary about using email with individuals outside the service organization, especially if it were to contain clinical material. There was low use of email directly with clients, and clinicians were ambivalent about incorporating email into therapy. The results suggest that it is timely to consider the utility and appropriateness of email communication with clients and external service providers, and to formulate guidelines and procedures to ensure the confidentiality of client information and the safety of clients and staff.