Untitled - D Ank Unlimited

U antigen
A rare MNs erythrocyte antigen present in fewer than
1% of African Americans and absent from Caucasian red
blood cells. When U antigen is not present, s antigen is not
expressed. Membrane sialoglycoprotein and glycophorins A
and B are requisite for U antigen expression.
U1 snRNP antibodies
Antibodies against 70-kDa A and C protein constituents of
the U1 small nucleoribonuclear proteins (U1 snRNPs). They
are commonly found in mixed connective tissue disease
(MCTD) or other syndromes related to systemic lupus erythematosus
(SLE) but rarely found in SLE. These antibodies
were formerly designated as RNP (ribonucleoprotein) or
nRNP (nuclear RNP) antibodies.
U1 snRNP autoantibodies
Autoantibodies against protein constituents (70-kDa A and
C) of the U1 small nuclear ribonucleoproteins (U1 snRNPs)
often found in systemic lupus erythematosus (SLE)–overlap
syndromes including mixed connective tissue disease
(MCTD) and less often SLE. U1 snRNP autoantibodies
were formerly termed RNP (ribonucleoprotein) or nRNP
(nuclear RNP) antibodies. Thirty-eight percent of sera that
react with protein constituents of U1 snRNPs also interact
with the RNA portions of snRNP particles. These U1
RNP antibodies are present only in SLE and SLE–overlap
syndromes. Unlike dsDNA antibodies, titers of antibodies
against 70-kDa or A constituents of U1 snRNP are
not helpful in monitoring disease activity or predicting
SLE flares. High-titer RNP antibodies are not linked to an
increased risk of fetal loss in SLE. Sm antibody sera do not
contain U1 RNA antibodies; 60% of sera with U1 smRNP
antibodies have small quantities of Sm antibodies and may
be designated anti-RNP/Sm sera. Besides Ul smRNP and
Sm antibodies, a less common U1/U2 snRNP antibody
reactive with Ul-A and U2-B proteins is present in SLE
and SLE–overlap syndromes. Specific T lymphocyte and
antibody epitopes are present in the 70-kDa protein of U1
snRNP. These epitopes are recognized in MCTD and to a
lesser degree in other systemic rheumatic diseases.
U2 snRNP antibodies
Antibodies against small nuclear ribonucleoparticles,
composed of U2 snRNA and eight other polypeptides. Anti
U2 sera that react with β polypeptides are often present in
overlap syndromes with myositis and may be associated
with antibodies against U1 snRNP polypeptides (70-kDa
A and C). U1 snRNP antibodies that interact with 70-kDa
polypeptide were previously designated RNP or nRNP and
are principal features of mixed connective tissue disease.
U2 snRNP autoantibodies
Antibodies against U2 snRNP (small nuclear ribonucleoproteins)
composed of U2 snRNA and eight associated
polypeptides. A′ and B′ are unique to U2 snRNP and six
(B′, B, D, E, F, and G) are shared with U1 and other snRNP.
U
Patients who have overlap syndromes with features of myositis
often manifest U2-specific antibodies that react with B′
with or without A′. These patients may also have antibodies
against U1 snRNP polypeptide (70-kDa A and C).
ubiquitin
A 7-kDa protein found free in the blood or bound to
cytoplasmic, nuclear, or membrane proteins united through
isopeptide bonds to numerous lysine residues. Ubiquitin
combines with a target protein and marks it for degradation.
It is a 76-amino-acid residue polypeptide found in all
eukaryotes but not in prokaryotes. Ubiquitin is found in
chromosomes covalently linked to histones, although the
function is unknown. Ubiquitin is present on the lymphocyte
homing receptor gp90Mel-14.
ubiquitin antibodies
Antibodies present in 79% of patients with systemic
lupus erythematosus (SLE) that may facilitate the diagnosis
of SLE when double-stranded DNA (dsDNA)
antibodies are also present. Ubiquitin antibodies may be
inversely related to dsDNA antibodies and disease activity.
Immunohistochemical staining revealed the presence of
intracellular ubiquitinated filamentous inclusions in human
chronic neurodegenerative diseases (e.g., in the motor
cortex and spine in motor neuron disease and in brain
cortical regions in one of the major newly recognized forms
of dementia, diffuse Lewy body disease). Ubiquitinated
filamentous inclusions have also been observed in some
liver and viral diseases (e.g., I hepatocytes in alcoholic
liver disease and in Epstein–Barr virus [EBV]-transformed
human lymphocytes). Ubiquitin-protein conjugates have
been found in the primary (azurophilic) lysosome-related
granules in mature polymorphonuclear neutrophils.
ubiquitination
The covalent linkage of several molecules of ubiquitin,
a small polypeptide, to a protein. Ubiquitinated protein is
marked for proteolytic degradation by proteasomes involved
in major histocompatibility complex (MHC) class I antigen
processing and presentation.
ubiquitin autoantibodies
Autoantibodies against ubiquitin, a highly conserved protein
of 76 amino acids found universally in eukaryotic cells present
among antibodies of 29 to 79% of patients with systemic
lupus erythematosus (SLE) patients. An inverse correlation
is believed to exist between ubiquitin antibodies assicuated
with disease activity and dsDNA antibodies. Enzyme
immunoassay (EIA) and immunoblotting are the methods of
choice to detect ubiquitin autoantibodies. Renal biopsies in
29% of lupus nephritis patients reveal ubiquitin autoantibodies
which points to a possible role in lupus nephritis.
UCHL1 anti-human T cell (CD45RO)
A mouse monoclonal antibody that recognizes specifically
the 180-kDa isoform of CD45 (leukocyte common antigen).
The 180-kDa glycoprotein occurs on most thymocytes and
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U