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L Hood

Publications and source records attributed to L Hood.

At least 361 records · Page 20Linked to original sources
PubMed1980

Human fibroblastoid interferon: immunosorbent column chromatography and N-terminal amino acid sequence.

Three mice and one rabbit were inoculated with purified human fibroblastoid interferon. Neutralizing activity to human fibroblastoid interferon was observed in the serum of these animals with the rabbit showing the highest anti-interferon titers (10(6) neutralizing units/mL). Rabbit antiserum was coupled to cyanogen bromide activated Sepharose, and the resulting material was tested for use in the purification of human fibroblastoid interferon. Pure interferon obtained by this procedure was analyzed, and we report the sequence of the first 13 N-terminal amino acid residues of this protein.

Amino Acid Sequence↗
PubMed1980

Structural correlates of cross-reactive and individual idiotypic determinants on murine antibodies to alpha-(1 leads to 3) dextran.

For the first time V-region amino acid sequence differences have been correlated with the expression of cross-reactive and individual idiotypes through an analysis of 12 dextran-binding proteins. This correlation has been possible because of the apparent sequence identity of the corresponding lambda chains. Expression of a cross-reactive idiotype was localized to two residues and/or a carbohydrate in the second hypervariable region of the heavy chain. Two individual idiotypes correlate with the two amino acids within the third hypervariable region that comprises the D segment of the dextran-binding proteins. These results demonstrate that idiotype reagents can recognize two amino acid differences within V and D segments of classical variable regions. In anti-dextran antibodies, cross-reactive idiotypes involve V-region determinants, whereas individual idiotype determinants correlate with D-segment variation.

Amino Acid Sequence↗
PubMed1980

Mouse Cmu heavy chain immunoglobulin gene segment contains three intervening sequences separating domains.

The IgM molecule is composed of subunits made up of two light chain and two heavy chain (mu) polypeptides. The mu chain is encoded by several gene segments--variable (V), joining (J) and constant (Cmu). The Cmu gene segment is of particular interest for several reasons. First, the mu chain must exist in two very different environments--as an integral membrane protein in receptor IgM molecules (micrometer) and as soluble serum protein in IgM molecules into the blood (mus). Second, the Cmu region in mus is composed of four homology units or domains (Cmu1, Cmu2, Cmu3 and Cmu4) of approximately 110 amino acid residues plus a C-terminal tail of 19 residues. We asked two questions concerning the organisation of the Cmu gene segment. (1) Are the homology units separated by intervening DNA sequences as has been reported for alpha (ref. 5), gamma 1 (ref. 6) and gamma 2b (ref. 7) heavy chain genes? (2) Is the C-terminal tail separated from the Cmu4 domain by an intervening DNA sequence? If so, DNA rearrangements or RNA splicing could generate hydrophilic and hydrophobic C-terminal tails for the mus and micrometer polypeptides, respectively. We demonstrate here that intervening DNA sequences separate each of the four coding regions for Cmu domains, and that the coding regions for the Cmu4 domains and the C-terminal tail are directly contiguous.

Animals↗
PubMed1980

An immunoglobulin heavy-chain gene is formed by at least two recombinational events.

The events of B-cell differentiation can be reconstructed in part through an analysis of the organisation of heavy-chain gene segments in differentiated B cells. A mouse immunoglobulin alpha heavy-chain gene is composed of at least three noncontiguous germ-line DNA segments--a VH gene segment, a JH gene segment associated with the Cmu gene segment, and the C alpha gene segment. These gene segments are joined together by two distinct types of DNA rearrangements--a V-J joining and a CH switch.

Animals↗
PubMed1980

The joining of V and J gene segments creates antibody diversity.

The variable regions of mouse kappa (kappa) chains are coded for by multiple variable (V) gene segments and multiple joining (J) gene segments. The V kappa gene segments code for residues 1 to 95; the J kappa gene segments code for residues 96 to 108 (refs 1-3). This gene organisation is similar to that encoding the V lambda regions. Diversity in V kappa regions arises from several sources: (1) there are multiple germ-line V kappa gene segments and J kappa gene segments; (2) combinatorial joining of V kappa gene segments with different germline J kappa gene segments; and possibly, (3) somatic point mutation, as postulated for V lambda gene segments. Also, from a comparison of the number of germ-line J kappa gene segments and amino acid sequences, it has been suggested that J kappa region sequences may be determined by the way V kappa and J kappa gene segments are joined. This report supports this model by directly associating various J kappa sequences with given J kappa gene segments.

Animals↗
PubMed1980

Amino acid sequence of homogeneous antibodies to dextran and DNA rearrangements in heavy chain V-region gene segments.

The complete variable region sequences from ten antibodies and two myeloma proteins binding alpha-1,3 dextran have been determined. The diversity patterns of these homogeneous antibody molecules suggest that the variable regions of heavy chains are encoded by separate variable (V) and joining (J) gene segments. The most striking feature of these data is the extensive sequence variability of a region that we denote the D (diversity) segment which is located at the junction between the V and J segments in the centre of the third hypervariable region. The D segment diversity may arise from a novel somatic mutational mechanism or may be encoded by multiple D gene segments. For the first time, the amino acid sequence correlates of several V region idiotypes are determined.

Amino Acid Sequence↗
PubMed1980

Microsequence analysis of Ia antigens from three strains of rats.

Homologues of Ia antigens of the mouse are identified in three rat strains by partial N-terminal amino acid sequence analysis. Ia antigens of the rat were isolated by indirect immune precipitation using specific rat alloantisera. Rat Ia antigens consist of two components, alpha and beta, which have respective mol. wts. of approximately 35 000 and 28 000. Partial N-terminal sequence analysis of each of the alpha components of the H-1a, H-11 and H-1n haplotypes yields a single, apparently homogeneous sequence which is identical among the three haplotypes and is strikingly homologous to the alpha polypeptides of the I-E subregion of mouse and to the human polypeptide, p34. Partial N-terminal sequence analysis of the beta components shows that a mixture of polypeptides is present for each haplotype. There are differences in the beta sequences among the three haplotypes and potential homologies between the rat beta sequences and the sequences of the beta polypeptides of the I-A and I-E subregions of mouse. These obserations imply that the rat has at least two distinct groups of Ia molecules. The organization of genes encoding the Ia polypeptides in the major histocompatibility complex of the rat is discussed.

Amino Acid Sequence↗
PubMed1980

Structure of Ia antigens from the rat. Mouse alloantisera demonstrate at least two distinct molecular species.

Ia antigens isolated from spleen cells of rats and mice are composed of two polypeptide chains, designated alpha and beta. Mouse alloantisera specific for the I-Ak and I-Ek subregions react with two distinct groups of rat Ia antigens, designated A-like and E-like, respectively. Two-dimensional gel electrophoresis and peptide map analysis demonstrate that the A-like antigens of rat are distinct from the E-like antigens. Both rat Ia antigens react with alloantiserum produced in rats congenic for the major histocompatibility complex (MHC). These results demonstrate for the first time that two distinct Ia antigens are present in the rat. Accordingly, the rat, like the mouse, may have Ia antigens encoded by at least two subregions of the rat MHC. The existence of multiple Ia gene products in rats is revealed by chemical techniques even in the absence of formal genetic evidence of more than one I subregion in the rat.

Animals↗
PubMed1980

A computer simulation of evolutionary forces controlling the size of a multigene family.

A Monte Carlo-type simulation of the evolution of a multigene family was performed. The model was designed to study the selective forces which may control the size of a multigene family. As expected, we find that direct selection on the size of the multigene family can control its size. More important, we find that selection acting upon the family as a single functional unit, in conjunction with homologous but unequal crossing over, can also control the size of a multigene family.

Animals↗
PubMed1980

An immunoglobulin heavy chain variable region gene is generated from three segments of DNA: VH, D and JH.

We have determined the sequences of separate germline genetic elements which encode two parts of a mouse immunglobulin heavy chain variable region. These elements, termed gene segments, are heavy chain counterparts of the variable (V) and joining (J) gene segments of immunoglobulin light chains. The VH gene segment encodes amino acids 1-101 and the JH gene segment encodes amino acids 107-123 of the S107 phosphorylcholine-binding VH region. This JH gene segment and two other JH gene segments are located 5' to the mu constant region gene (Cmu) in germline DNA. We have also determined the sequence of a rearranged VH gene encoding a complete VH region, M603, which is closely related to S107. In addition, we have partially determined the VH coding sequences of the S107 and M167 heavy chain mRNAs. By comparing these sequences to the germline gene segments, we conclude that the germline VH and JH gene segments do not contain at least 13 nucleotides which are present in the rearranged VH genes. In S107, these nucleotides encode amino acids 102-106, which form part of the third hypervariable region and consequently influence the antigen-binding specificity of the immunoglobulin molecule. This portion of the variable region may be encoded by a separate germline gene segment which can be joined to the VH and JH gene segments. We term this postulated genetic element the D gene segment, referring to its role in the generation of heavy chain diversity. Essentially the same noncoding sequences are found 3' to the VH gene segment and as inverse complements 5' to two JH gene segments. These are the same conserved nucleotides previously found adjacent to light chain V and J gene segments. Each conserved sequence consists of blocks of seven and ten conserved nucleotides which are separated by a spacer of either 11 or 22 nonconserved nucleotides. The highly conserved spacing, corresponding to one or two turns of the DNA helix, maintains precise spatial orientations between blocks of conserved nucleotides. Gene segments which can join to one another (VK and JK, for example) always have spacers of different lengths. Based on these observations, we propose a model for variable region gene rearrangement mediated by proteins which recognize the same conserved sequences adjacent to both light and heavy chain immunoglobulin gene segments.

Animals↗
PubMed1980

The immunoglobulin mu chains of membrane-bound and secreted IgM molecules differ in their C-terminal segments.

The B lymphocytes synthesizes two forms of IgM molecules during its development from a stem cell to a mature antibody-secreting plasma cell. The monomeric receptor IgM molecule is affixed to the plasma membrane and triggers the later stages of B cell differentiation, whereas the pentameric secreted IgM molecule is an effector of humoral immunity. The structural differences between membrane-bound and secreted IgM molecules are reflected in the differences between their heavy or mu chains. We have previously determined the complete amino acid sequence of a murine secreted mu (microsecond) chain. In this study, we have compared the structures of the secreted and membrane-bound mu (micron) heavy chains by peptide mapping, micro-sequence and carboxypeptidase analyses. These studies demonstrate that the micron and microsecond chains are very similar throughout their VH, C mu 1, C mu 2, C mu 3 and C mu 4 domains. The micron and microsecond chains differ in the amino acid sequence of their C-terminal segments. These studies in conjunction with those carried out on the micron and microsecond mRNAs and the C mu gene suggest that the micron and microsecond chains from a given B cell are identical except for their 41 and 20 residue C-terminal segments, respectively. The amino acid sequence of the 41 residue C membrane terminal segment predicted from the corresponding micron mRNA is in agreement with all the protein studies reported in this paper.

Amino Acid Sequence↗
PubMed1980

Two mRNAs with different 3' ends encode membrane-bound and secreted forms of immunoglobulin mu chain.

During differentiation, B lymphocytes undergo a shift from expression of membrane-bound IgM to IgM secretion. The mu chains of membrane and secreted IgM, mum and mus, respectively, differ in the amino acid sequence of their carboxy terminal regions. In this paper, we demonstrate that mum and mus heavy chains are encoded by separate mRNAs of 2.7 and 2.4 kb, respectively. Restriction mapping and sequence analysis of mu cDNA clones from a myeloma tumor that produces both types of mu chain indicate that the mum and mus mRNAs are identical throughout the coding region up to the 3' end of the fourth constant region (Cmu 4) domain, but differ in their C terminal coding and 3' untranslated segments. From the nucleotide sequence of the mum cDNA clone, we predict the amino acid sequence of the 41-residue mum C terminal segment or "M" (membrane) segment. This sequence has characteristics consistent with its being a transmembrane peptide. Thus the mus chain has a 20-residue hydrophilic C terminal segment after the Cmu 4 domain, and the mum chain has a 41-residue C terminal segment containing a hydrophobic sequence. We propose that comparable C terminal segments also will be found in other membrane-bound immunoglobulin heavy chains.

Animals↗
PubMed1980

Organization of kappa light chain genes in germ-line and somatic tissue.

We studied the organization of the kappa light chain genes in germ-line (sperm) and somatic (embryo) tissues. We constructed a plasmid containing a DNA insert coding for the kappa chain MOPC 167 and used the Southern blotting technique to determine the organization of kappa variable and constant region genes. In the haploid genome of the mouse there is only one constant region gene detectable and it has the same organization in sperm and embryo DNAs. There are several variable region genes in sperm and embryo that are related to the Vk167 gene. The organization of the V genes in sperm and embryo DNAs is identical. These results show that there is no rearrangement of variable region genes (or "minigenes") during early embryogenesis.

Alleles↗
PubMed1980

N-Terminal sequence of human big gastrin: sequence, synthetic and immunochemical studies.

The previously assigned structure of human big gastrin is revised as a result of sequencing and immunological studies on synthetic peptides. A nonadecapeptide has been synthesized and found to have full immunochemical potency compared with natural human G34 in a radioimmunoassay which is specific for the N-terminal sequence. Syntheses of the peptides were achieved using the stepwise procedure with benzyloxycarbonyl-amino acids and fragment couplings mediated mainly by the dicyclohexylcarbodiimide procedure in the presence of either N-hydroxysuccinimide or 1-hydroxybenzotriazole. Purification of the peptide fragments was by Sephadex LH-20 chromatography and removal of protecting groups was effected using 90% trifluoroacetic acid in the presence of scavengers. Purification of the nonadecapeptide was achieved by high performance liquid chromatography.

Amino Acid Sequence↗