Hybrid immunoglobulins with moving parts

A chimeric polypeptide consisting of, from its N-terminus to C-terminus:

• a. a human IgG Fc polypeptide beginning with the sequence selected from the group consisting of CDKTHTCPPCP (residues 1-11 of SEQ ID NO:35), CCVECPPCP (residues 1-9 of SEQ ID NO:53), CPRCP (residues 1-5 of SEQ ID NO:74), CPSCP (residues 1-5 of SEQ ID NO:89), CPPCP (residues 1-5 of SEQ ID NO:104), or CP (residues 1-2 of SEQ ID NO:112), joined at its C-terminus by a peptide bond to
• b. the N-terminus of the polypeptide encoded by a human IgG M1 exon or a portion of the polypeptide encoded by a human IgG M1 exon, having a C-terminal X-terminus wherein:
• (a) the polypeptide encoded by the human IgG M1 exon having a C-terminal X-terminus consists of the sequence ELQLEESCAEAQDGELDGX (residues 227 to 245 of SEQ ID NO:
• 138) wherein X is a cysteine, homocysteine, selenocysteine, or homoselenocysteine, or (b) the portion of the polypeptide encoded by the human IgG M1 exon having a C-terminal X-terminus consists of the sequence ELQLEESC (residues 221 to 228 of SEQ ID NO:
• 135).