Provided herein are cell surface conjugates containing a cell surface molecule and at least one agent, such as at least one affinity tag, and engineered cells expressing such cell surface conjugates. In some embodiments, the cell surface molecule does not contain an intracellular signaling domain or is not capable of mediating intracellular signaling. In some embodiments, the cells engineered to contain the cell surface conjugate, such as T cells, further contain a genetically engineered recombinant receptor that specifically binds to antigens, such as a chimeric antigen receptor (CAR). Also provided are methods of detecting, identifying, selecting or targeting cells expressing the cell surface conjugates, such as in connection with methods of manufacturing engineered cells or in connection with administration of such cells to subjects, including methods of adoptive cell therapy.

Fibronectin type III (.sup.10Fn3) binding domains having novel designs that are associated with reduced immunogenicity are provided. The application describes alternative .sup.10Fn3 binding domains in which certain immunogenic regions are not modified when producing a binder in order to maintain recognition as a self antigen by the host organism. The application also describes .sup.10Fn3 binding domains in which HLA anchor regions have been destroyed thereby reducing the immunogenic contribution of the adjoining region. Also provided are .sup.10Fn3 domains having novel combinations of modified regions that can bind to a desired target with high affinity.

Fibronectin type III domains (FN3) that specifically bind to serum albumin, related polynucleotides capable of encoding serum albumin-specific FN3 domains, cells expressing the FN3 domains, as well as associated vectors, detectably labeled FN3 domains and FN3 domains fused to a heterologous moiety are useful in extending the half-life of molecules in diagnostic and therapeutic applications.

The invention features soluble fusion protein complexes comprising at least two soluble fusion proteins. For example, the first fusion protein is an anti-CD3 antibody covalently linked to an interleukin-15 (IL-15) polypeptide or functional fragment thereof. The second fusion protein comprises a binding domain that recognizes disease antigens, wherein this domain is covalently linked to a soluble interleukin-15 receptor alpha (IL-15Rα) polypeptide or a functional fragment thereof. One or both of the first and second fusion proteins further includes an immunoglobulin Fc domain or a functional fragment thereof, and the IL-15 domain of first fusion protein binds to the soluble IL-15Rα domain of the second fusion protein to form a soluble fusion protein complex. The invention further provides methods for making and using the complexes of the invention.

D domain (DD) containing polypeptides (DDpp) that specifically bind targets of interest (e.g., BCMA, CD123, CS1, HER2, AFP, and AFP p26) are provided, as are nucleic acids encoding the DDpp, vectors containing the nucleic acids and host cells containing the nucleic acids and vectors. DDpp such as DDpp fusion proteins, are also provided as are methods of making and using the DDpp. Such uses include, but are not limited to diagnostic and therapeutic applications.

Wnt signaling agonist compositions and methods for their use are provided. Wnt signaling agonists of the invention comprise a frizzled binding moiety, which is fused or conjugated to an LRP5 or LRP6 binding moiety.

This disclosure features fusion proteins comprising a base protein linked to or incorporated in a CH2 scaffold of IgG. The CH2 scaffold can derive from the macaque CH2 domain of IgG. The fusion proteins can effectively bind a single or multiple targets, and can be engineered to regulate effector functions as desired. The fusion proteins can have an increased serum half-life, solubility, stability, protease resistance, and/or expression as compared to the scaffolds alone and/or as compared to the base protein alone. This disclosure also features fusion proteins comprising a base protein, a CH2 scaffold and a discrete polyethylene glycol (dPEG) linked to the scaffold via a serine, tyrosine, cysteine, lysine, or a glycosylation site of the scaffold. This disclosure additionally features scaffolds linked to a discrete polyethylene glycol (dPEG) via a serine, tyrosine, cysteine, or lysine of the scaffolds or a glycosylation site of the scaffold.

An RNA and protein delivery system utilizing an RNA-protein complex having a higher-order structure, and an RNA-protein complex having a novel higher-order structure.

Bispecific EGFR/c-Met antibodies and methods of making and using the molecules.

Provided are compositions and methods for labeling an endogenous protein, in particular, in a live cell, or for ablating an endogenous or target protein. The compositions relate to a fusion protein having a binding moiety such as an antibody, an antigen binding fragment of an antibody or an antibody mimetic that recognizes the endogenous or target protein.