Keyhole limpet hemocyanin type 2 (KLH2): detection and immunolocalization of a labile functional unit h.
Keyhole limpet hemocyanin (KLH) is a mixture of two hemocyanin isoforms, termed KLH1 and KLH2. Within KLH1 eight oxygen-binding functional units (FUs), 1-a to 1-h, have been identified, in contrast to KLH2, which was previously thought to be organized in seven FUs (2-a to 2-g). By limited proteolysis of KLH2 subunits, isolation of the polypeptide fragments, and N-terminal sequencing, we have now identified an eighth FU of type h, with a molecular mass of 43 kDa. This is unusually small for a FU h from a gastropodan hemocyanin. It is also shown that KLH2 didecamers can be split into a stable and homogeneous population of decamers by dialysis against 50 mM Tris/HCl, pH 7.5, in the absence of divalent cations. Electron microscopic immunolocalization using a specific monoclonal antibody reveals that FU KLH2-h is located at the collar of the decamer.
Gebauer
W
W
Institute of Zoology, University of Mainz, Mainz, D-55099, Germany. wolfgang@uzomai.biologie.uni-mainz.de
Harris
J R
JR
Geisthardt
G
G
Markl
J
J
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D010450:Endopeptidases / Q000378:metabolism; D006433:Hemocyanins / Q000737:chemistry* / Q000276:immunology; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D008974:Mollusca; D020033:Protein Isoforms / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification; D020836:Protein Structure, Quaternary; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D020033:Protein Isoforms; D006433:Hemocyanins; D010450:Endopeptidases; C032808:keyhole-limpet hemocyanin