Proteinoplasts

Plant cells bear unique structures in cell biology due to the presence of a cell wall, a large central vacuole, and plastids. There are many specialised organelles present in plant cells that play an important role in the survival of the plant cells. Among these cell organelles, plastids are the specialised organelles that are structurally double membraned organelles. They are present ubiquitously in the plant cells and play a major role in storing food, metabolism of energy, and various other biological reactions. These plastids are classified into many categories, and proteinoplast (also termed proteoplasts, aleuroplasts, and aleuroplast) is one of the broadest categories of plastids in plant cells. There are three major categories of plastids (based on size, function, physical characteristics, the presence or absence of the biological pigments, and development stages), i.e. Leucoplasts, Chromoplasts and Chloroplasts. Proteinoplasts belong to the broadest category of plastids, i.e. leucoplasts.  

Plastids

The plant cells in biology have more distinctive features than the animal cells as the plant cells include a cell wall, a large central vacuole, and cell organelles such as plastids, chloroplasts, etc. The major organelle which helps in the photosynthesis process of plant cells are chloroplasts. Another important cell organelle for the photosynthesis process is plastids that remain undiscovered for a long period. The green pigment that is chlorophyll is crucial for the photosynthesis process, and these are contained in the chloroplasts. Plastids are double-membrane organelles that help prepare and store food in plant cells during the photosynthesis process. Plastids contain different pigments which can change the colour of the plant cell. 

A few important categories of plastids

Plastids are organelles that are ubiquitous present in plant cells as they are very crucial for the synthesis and storage of food in plants. A few important classes based on the presence and absence of the biological pigments are classified into the following categories: 

• Chloroplasts: These plastids are present in the mesophyll of the plant cells and help in preparing food for the plant cells for light energy.

• Chromoplasts: These plastids convert into chloroplasts and play a key role in synthesising and storing large amounts of carotenoid pigments. These carotenoid pigments provide different colours to the plants (leaves, fruits, etc.), which help in attracting pollinators. 

• Leucoplasts: Unlike chromoplasts and chloroplasts, they are colourless plastids, therefore present in non-photosynthetic parts of a plant. They play an important role in the storage of food in plants, wherein food can be in the form of starch, lipids, proteins, etc.

• Amyloplasts (help in synthesising and storing starch), Elaioplasts (they help in synthesising and storing fats, oils, etc.), Proteinoplasts (they store and synthesise proteins), and Tannosomes. 

Proteinoplasts 

Proteinoplasts definition involves that the proteinoplasts are the double membranous organelle (plastids) of a plant cell. Proteinoplast further includes that they are colourless pigments and stores proteins. Proteinoplasts are classified under the leucoplasts category of plastids. These are the colourless pigments and therefore are mostly found in those parts of the plants which are colourless or non-photosynthetic parts of the plant. Proteinoplasts help in the storage and synthesis of proteins in plant cells. Proteinoplasts, thus act as a site for enzymatic activity due to these proteins. They are mostly found in the seeds, such as peanuts, pulses, etc. The important role of the proteinoplasts is that they play a crucial role in the storage of food and the metabolism of energy in the plant cells.

Proteinoplasts can be referred to as the leucoplasts that store and synthesise proteins for the plant cells only. These proteinoplasts contain crystalline bodies of the proteins and act as a site for enzymatic activities. Proetinoplasts remained undiscovered for a very long time and were identified in the 1960s. Most scientists have confirmed proteinoplasts as a sole protein reservoir, which means they are only a reservoir of proteins. Unlike other plastids, the proteinoplasts are colourless pigments and store only protein as and when required by the plant cell. These proteinoplasts are mostly found in the seeds of a plant.

Conclusion 

Given the above-detailed overview of the proteinoplasts, we understand that the Plastids are the important cell organelles that are structurally double membraned organelles. They play a crucial part in the storage of food, metabolism of energy, and various other biological reactions. These plastids are classified into many categories, and proteinoplasts classified under leucoplasts are one of the broadest categories of plastids. Proteinoplasts are colourless pigments or non-photosynthetic pigments. Proteinoplasts help in the storage and synthesis of proteins in plant cells. Thus, proteinoplasts act as an important site for enzymatic activity due to these proteins.