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A structural and functional homologue of vertebrate alpha 2-macroglobulin (alpha 2M) has been identified in the hemolymph and blood cells of the arthropod Limulus polyphemus, one of the oldest living fossil invertebrates (Quigley, J. P., and Armstrong, P. B. (1985) J. Biol. Chem. 260, 12715-12719). The subunit molecular mass is 185 kDa. The native molecular mass, determined by scanning transmission electron microscopy (STEM) under conditions in which the linear relationship between the STEM large angle detector signal and specimen mass thickness allows the determination of the total macromolecular mass, was 354 +/- 35 kDa. Sedimentation equilibrium measurements gave a value of 366 kDa, independent of solute concentration. Sedimentation velocity experiments indicated a homogeneous component with a frictional ratio of 1.41. Thus, the native structure appears to be a dimer, with a somewhat extended conformation. The behavior during gel permeation chromatography was anomalous, yielding an apparent molecular mass approximately half-way between that expected for the dimeric and tetrameric configurations. Transmission electron microscopy of negatively stained preparations revealed a dimeric butterfly-like structure that collapsed following reaction with chymotrypsin.
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
January 1990,
Comparative biochemistry and physiology. B, Comparative biochemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
July 1993,
Molecular immunology,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
October 1995,
The Biological bulletin,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
October 1985,
The Journal of biological chemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
June 1995,
The Journal of biological chemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
October 1990,
Biochemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
December 1996,
European journal of biochemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
July 1983,
The Journal of biological chemistry,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
October 1976,
Experientia,
P B Armstrong, and
W F Mangel, and
J S Wall, and
J F Hainfield, and
K E Van Holde, and
A Ikai, and
J P Quigley
October 1991,
The Journal of biological chemistry,
