Abstracts (complete list) - Wissenschaft Online

Simone Klöter, Max v. Holleben, Bernhard Reis, Klaus Pfeffer, Sandra Beer
Interaction analysis of the adaptor protein SLy2
Adaptive immunity is crucial for protective host defense and the development of
immunological disorders. An increasing number of molecules with SH2 or SH3 domains
involved in the T or B cell receptor signal transduction pathways have been discovered
in the last years.
SLy2 (SH3 domain protein expressed in lymphocytes 2) was recently identified as an
SH3- and SAM-domain containing protein. In humans, the SLy2 gene is located on
chromosome 21, in mice on chromosome 16. SLy2 is expressed in hematopoetic tissues
as well as in brain, lung and pancreas. Additionally, SLy2 is up-regulated in activated
human B cells treated with IL-4, CD40L and anti-IgM. Therefore, SLy2 might be a
component of signalling cascades that lead to B cell activation and differentiation.
To elucidate the function of SLy2 we screened for possible interaction partners of this
adaptor protein. Considering the fact that SH3- and SAM-domains can mediate
homodimerization of proteins we performed coimmunoprecipitations with differentially
tagged SLy2 constructs. We were able to show the formation of SLy2 homodimers in
293T cells via the SH3 domain.
In order to identify further interaction partners of SLy2 a Yeast Two Hybrid Screen with
a mouse T cell lymphoma library was carried out. This resulted in two putative
interaction partners of SLy2: Sin3-associated polypeptide p30 (SAP30) and ribosomal
protein L12 (rpL12). SAP30 is a component of the histone deacetylase complex
including HDAC1, HDAC2, mSin3 as well as other proteins and consequently is capable
of repressing the transcription of different genes. rpL12 is associated with the assembly
of the 40S and 60S subunit of eukaryotic ribosomes. The interactions of SLy2 with both
proteins were confirmed by coimmunoprecipitations with lysates from transiently
transfected 293T cells. This interaction of SLy2 with SAP30 and rpL12 insinuates
transcriptional and/or translational regulatory functions of SLy2.