Knowledge-Rich Similarity-Based Classification

This paper proposes to enhance similarity-based classification with different types of imperfect domain knowledge. We introduce a hierarchy of knowledge types and show how the types can be incorporated into similarity measures. Furthermore, we analyze how properties of the domain theory, such as partialness and vagueness, influence classification accuracy. Experiments in a simple domain suggest that partial knowledge is more useful than vague knowledge. However, for data sets from the UCI Machine Learning Repository, we show that even vague domain knowledge that in isolation performs at chance level can substantially increase classification accuracy when being incorporated into similarity-based classification

Role of Adaptor Complex AP-3 in Targeting Wild-Type and Mutated CD63 to Lysosomes

CD63 is a lysosomal membrane protein that belongs to the tetraspanin family. Its carboxyterminal cytoplasmic tail sequence contains the lysosomal targeting motif GYEVM. Strong, tyrosine-dependent interaction of the wild-type carboxyterminal tail of CD63 with the AP-3 adaptor subunit μ3 was observed using a yeast two-hybrid system. The strength of interaction of mutated tail sequences with μ3 correlated with the degree of lysosomal localization of similarly mutated human CD63 molecules in stably transfected normal rat kidney cells. Mutated CD63 containing the cytosolic tail sequence GYEVI, which interacted strongly with μ3 but not at all with μ2 in the yeast two-hybrid system, localized to lysosomes in transfected normal rat kidney and NIH-3T3 cells. In contrast, it localized to the cell surface in transfected cells of pearl and mocha mice, which have genetic defects in genes encoding subunits of AP-3, but to lysosomes in functionally rescued mocha cells expressing the δ subunit of AP-3. Thus, AP-3 is absolutely required for the delivery of this mutated CD63 to lysosomes. Using this AP-3–dependent mutant of CD63, we have shown that AP-3 functions in membrane traffic from the trans-Golgi network to lysosomes via an intracellular route that appears to bypass early endosomes