No abstract

The C-type lectin family is a group of animal proteins which can be distinguished from other lectins by the presence of a Ca2+-dependent carbohydrate recognition domain (CRD) in their protein sequence. They are classified into 17 groups according to their domain architecture and have a wide variety of functions. The human chondrolectin gene encodes transmembrane (CHODL, CHODLf) and soluble proteins (CHODLDeltaE, CHODLfDeltaE) belonging to the family of C-type lectins because of the presence of one CRD domain in their N-terminal region. The CHODL splice variants (CHODLf, CHODLDeltaE and CHODLfDeltaE) are differentially expressed in T lymphocytes. The transmembrane-containing isoform CHODLf is localized in the ER-Golgi apparatus. CHODLDeltaE and CHODLfDeltaE are devoid of the transmembrane domain and terminate in QDEL, an ER retention signal. In this paper we have investigated the expression of the CHODLDeltaE/CHODLfDeltaE protein. This variant localizes in the late endoplasmic reticulum. We detected the protein in spleen and tonsils in a small population of lymphocytes. Moreover, the isoform seems to be differentially expressed in thymocytes and lymphocytes suggesting an important biological function during T cell development.

Mouse chondrolectin (chodl) was isolated out of the tail tip of fourday old 129/SvJ mice as a by-product of a PCR-based subtractive cDNA library screening. The gene is predominantly expressed in adult skeletal muscle, heart, testes and lungs and in embryonic stadia. Chodl is the mouse homologue of human chondrolectin (CHODL), a gene that encodes for a type Ia transmembrane protein and that is expressed in human testis, prostate, heart and skeletal muscle tissue. CHODL-splice variants (CHODL f , CHODL fΔE , CHODL ΔE ) are detected in human leukocytes. The proteins of the chondrolectin family belong to the family of C-type lectins. As the members of this protein family are important for a wide array of biological processes, the function of chodl was investigated by searching for its protein interaction partners. The β-subunit of Rab geranylgeranyl transferase (Rabggtb) was isolated 8 times after a complete Sos recruitment system (SRS) screen with the cytoplasmic domain of chodl. The interaction was confirmed with in vitro transcription/translation and co-immunoprecipitation (co-IP) experiments.