Adaptor Protein Complex sigma Subunits: A family of small adaptin protein complex subunits of approximately 19 KDa in size.Adaptor Protein Complex 3: An adaptor protein complex found primarily on perinuclear compartments.Adaptor Protein Complex 1: A clathrin adaptor protein complex primarily involved in clathrin-related transport at the TRANS-GOLGI NETWORK.Sigma Factor: A protein which is a subunit of RNA polymerase. It effects initiation of specific RNA chains from DNA.Adaptor Protein Complex 2: An adaptor protein complex primarily involved in the formation of clathrin-related endocytotic vesicles (ENDOSOMES) at the CELL MEMBRANE.DNA-Directed RNA Polymerases: Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).Adaptor Protein Complex 4: An adaptor protein complex involved in transport of molecules between the TRANS-GOLGI NETWORK and the endosomal-lysosomal system.Adaptor Protein Complex Subunits: The subunits that make up the large, medium and small chains of adaptor proteins.Adaptor Protein Complex delta Subunits: A family of large adaptin protein subunits of approximately 130-kDa in size. They have been primarily found as components of ADAPTOR PROTEIN COMPLEX 3.Adaptor Protein Complex mu Subunits: A family of medium adaptin protein subunits of approximately 45 KDa in size. They have been primarily found as components of ADAPTOR PROTEIN COMPLEX 3 and ADAPTOR PROTEIN COMPLEX 4.Adaptor Proteins, Vesicular Transport: A class of proteins involved in the transport of molecules via TRANSPORT VESICLES. They perform functions such as binding to the cell membrane, capturing cargo molecules and promoting the assembly of CLATHRIN. The majority of adaptor proteins exist as multi-subunit complexes, however monomeric varieties have also been found.Adaptor Protein Complex gamma Subunits: A family of large adaptin protein subunits of approximately 90 KDa in size. They have been primarily found as components of ADAPTOR PROTEIN COMPLEX 1.Adaptor Protein Complex beta Subunits: A family of large adaptin protein complex subunits of approximately 90-130 kDa in size.Adaptor Protein Complex alpha Subunits: A family of large adaptin protein subunits of approximately 100 kDa in size. They have been primarily found as components of ADAPTOR PROTEIN COMPLEX 2.Adaptor Proteins, Signal Transducing: A broad category of carrier proteins that play a role in SIGNAL TRANSDUCTION. They generally contain several modular domains, each of which having its own binding activity, and act by forming complexes with other intracellular-signaling molecules. Signal-transducing adaptor proteins lack enzyme activity, however their activity can be modulated by other signal-transducing enzymes