Molecular cloning and characterization of a novel marsupial milk protein gene

Collet, Christopher; Joseph, R.; Nicholas, Kevin R.

doi:10.1016/0006-291x(89)91822-6

Cited by 21 publications

(13 citation statements)

References 7 publications

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“…The early lactation protein has sequence homology with the Kunitz family of protease inhibitors (Piotte & Grigor 1996) whereas late lactation protein and trichosurin, along with -lactoglobulin, belong to the lipocalin family of secretory ligand-binding proteins (Piotte et al 1997a). The possum late lactation protein is a homologue of a tammar wallaby (Macropus eugenii) whey protein which is only expressed in phase 3 of lactation (Nicholas et al 1987, Collet et al 1989). It has not yet been determined whether other marsupials express either trichosurin or early lactation protein.…”

Section: Introductionmentioning

confidence: 99%

Differential expression of milk protein genes during lactation in the common brushtail possum (Trichosurus vulpecula)

Demmer

Ik²,

Ginger³

et al. 1998

Journal of Molecular Endocrinology

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In the common brushtail possum (Trichosurus vulpecula) lactation lasts for 200 days and consists of two distinct phases. Milk composition changes dramatically between phase 2 and 3, which correspond to early and late lactation respectively (phase 1 corresponds to pregnancy). RNA expression patterns have been established for eight major milk protein genes throughout lactation in possum mammary glands. The levels of mRNA expressed from two genes, encoding the early and late lactation proteins, were differentially regulated during lactation, with peak RNA levels occurring in phase 2 and 3 of lactation respectively. Expression of these two RNA transcripts did not overlap, and neither gene was expressed at significant levels between days 116 to 125, suggesting that the transition from phase 2 to phase 3 of lactation occurs at this time. The level of lysozyme, -lactalbumin and trichosurin mRNA increased in phase 3 of lactation, whereas the levels of -lactoglobulin, -casein and -casein mRNA remained constant throughout lactation. In the non-suckled gland, expression of milk protein genes was greatly reduced by day 6 of lactation. In conclusion, the early and late lactation protein genes are good markers for phase 2 and 3 of lactation, with the transition between these phases occurring around day 120 of lactation in the possum.

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Section: Introductionmentioning

confidence: 99%

Differential expression of milk protein genes during lactation in the common brushtail possum (Trichosurus vulpecula)

Demmer

Ik²,

Ginger³

et al. 1998

Journal of Molecular Endocrinology

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“…The gene encoding LLP was isolated from a tammar wallaby mammary gland cDNA library, using an oligonucleotide probe, as reported by Collet et al (1989). Tissue culture of a tammar cell line, preparation of chromosome spreads and the tritiated LLP probe, and in situ hybridization were performed as described by Sinclair et al ( 1988).…”

Section: Methodsmentioning

confidence: 99%

“…"Late" milk is characterized by an increased milk protein concentra tion, due partly to increased synthesis of proteins already present in "early" milk and, in part, to the appearance of a major whey protein (late lactation protein, or LLP) absent from the early stages of lactation (see Collet et al, 1989). This paper reports the cytogenetic location of this novel milk protein gene in the tammar.…”

mentioning

confidence: 99%

Chromosomal localization of the gene for late lactation protein (LLP) in the tammar wallaby <i>(Macropus eugenii</i><i>)</i>

Westerman

Spencer²,

Collet³

1991

Cytogenet Genome Res

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“…In some lipocalins, Arg139 is replaced by lysine, a change that does not disrupt the electrostatic interaction between these residues. In late lactation proteins from marsupials, Trp24 is uniquely replaced by tyrosine (Collet et al 1989;Beg and Shaw 1994), a change that is invariably linked with the replacement of the residue corresponding to Arg139 by proline. These coupled natural substitutions seem likely to reflect the conservation of a tertiary interaction between these sites by substitution of a Tyr-Pro stacking interaction (Thornton 1992) for the TrpArg aromatic-amine interaction.…”

Section: Environments Of Tryptophans Within the Three-dimensional Strmentioning

confidence: 99%

“…Substitutions of Leu for Trp67 and of His for Trp91 reflect a sequence change in Xenopus RBP, and Phe for Trp105 was based on structural conservation. Trp24 was replaced by Tyr, based on the previously discussed substitution in late lactation proteins from marsupials (Collet et al 1989) and by Phe and Leu to introduce a weakly fluorescent or nonfluorescent residue. These changes will also eliminate the H-bond between the indole nitrogen and the carbonyl oxygen of Phe20.…”

Section: Design and Characterization Of Mutantsmentioning

confidence: 99%

Role of conserved residues in structure and stability: Tryptophans of human serum retinol‐binding protein, a model for the lipocalin superfamily

et al. 2001

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Serum retinol binding protein (RBP) is a member of the lipocalin family, proteins with up-and-down ␤-barrel folds, low levels of sequence identity, and diverse functions. Although tryptophan 24 of RBP is highly conserved among lipocalins, it does not play a direct role in activity. To determine if Trp24 and other conserved residues have roles in stability and/or folding, we investigated the effects of conservative substitutions for the four tryptophans and some adjacent residues on the structure, stability, and spectroscopic properties of apo-RBP. Crystal structures of recombinant human apo-RBP and of a mutant with substitutions for tryptophans 67 and 91 at 1.7 Å and 2.0 Å resolution, respectively, as well as stability measurements, indicate that these relatively exposed tryptophans have little influence on structure or stability. Although Trp105 is largely buried in the wall of the ␤-barrel, it can be replaced with minor effects on stability to thermal and chemical unfolding. In contrast, substitutions of three different amino acids for Trp24 or replacement of Arg139, a conserved residue that interacts with Trp24, lead to similar large losses in stability and lower yields of native protein generated by in vitro folding. The results and the coordinated nature of natural substitutions at these sites support the idea that conserved residues in functionally divergent homologs have roles in stabilizing the native relative to misfolded structures. They also establish conditions for studies of the kinetics of folding and unfolding by identifying spectroscopic signals for monitoring the formation of different substructures. , multi-site mutants (indicating the substitution of X for residue m and Y for residue n); MG, molten globule state; PCR, polymerase chain reaction; GndHCl, guanidine hydrochloride. KeywordsArticle and publication are at http://www.proteinscience.org/cgi

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Molecular cloning and characterization of a novel marsupial milk protein gene

Cited by 21 publications

References 7 publications

Differential expression of milk protein genes during lactation in the common brushtail possum (Trichosurus vulpecula)

Differential expression of milk protein genes during lactation in the common brushtail possum (Trichosurus vulpecula)

Chromosomal localization of the gene for late lactation protein (LLP) in the tammar wallaby <i>(Macropus eugenii</i><i>)</i>

Role of conserved residues in structure and stability: Tryptophans of human serum retinol‐binding protein, a model for the lipocalin superfamily

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